The hidden costs of buying a SaaS that nobody warns you about
An itemized buyer's guide to what an inherited SaaS actually costs to keep alive each month, with real numbers from real listings.
You found a half built SaaS on Failedups. The seller wants $3k. The code runs, the domain is clean, two paying users are on the books. You wire the money, transfer the repo, and feel like a genius.
Then the first month of bills hits.
This is the part nobody warns first time buyers about. The asking price is the cheap part of the deal. The real cost is the monthly rent on the stack you just inherited. Here is the itemized list of what you are actually signing up for, with the numbers I have seen across roughly 80 acquisitions on the platform.
The monthly stack
Hosting
Most projects on Failedups are deployed on Vercel or Cloudflare. Vercel Hobby is free but breaks the moment you have a real user, because the function timeouts and bandwidth caps are designed to push you to Pro. Pro is $20 per seat per month, and you cannot run a team on it without adding seats. If the previous founder had two collaborators, that is $60 a month before you have served a single request.
Cloudflare Workers Paid is $5 a month, much cheaper, but the moment you start using D1, R2, or Workers AI in any volume, the per-request costs creep up. Budget $10 to $30 per month for a small product on Cloudflare, and $20 to $80 per month on Vercel.
Database
Supabase Pro is $25 a month. That gets you 8 GB of storage, daily backups, and seven days of point in time recovery. If the project has any real data, you will want PITR extended to 14 or 28 days, which adds $100 a month fast. Neon and Planetscale have similar tiers. The free tiers exist, but they pause your database after a week of inactivity, which is exactly what kills inherited side projects.
If you skip the paid tier, you are one accidental DELETE away from losing the user table.
AI and LLM bills
This is where buyers get blindsided. A “small but used” AI product can rack up $200 to $500 a month in OpenAI or Anthropic calls without you noticing. I bought a writing tool last year that had 40 weekly active users. The previous owner said inference was around $80 a month. By month two it was $340, because two of those users had started running it on their entire archive.
Set hard rate limits on day one. Cache aggressively. Move the cheap calls to Haiku or GPT 4 mini. The buyers who lose money on AI products almost always lose it here.
You need transactional email. Resend starts at $20 a month for 50k emails. Postmark is $15 to start. SendGrid technically has a free tier but the deliverability on the free tier is bad enough that your password resets land in spam. Budget $20 to $50 a month minimum, more if the product sends marketing email.
Analytics
PostHog Cloud is free up to 1M events, then about $0.0005 per event after. Plausible is $9 a month for the cheapest plan. Most inherited products have PostHog because it was free when the founder set it up, and they never noticed the bill clock starting once usage picked up. Check the actual event volume before you assume it is free.
Domain renewal
A domain is $14 a year. Sounds like nothing. The problem is that founders forget. I have watched two acquisitions where the new owner missed the renewal notice in their old inbox and the domain dropped. One of them got it back through a $200 redemption fee. The other did not.
Move the domain to your own registrar in week one. Set auto renew. Add a calendar reminder for 30 days before expiry as a backup.
Monitoring and error tracking
Better Stack starts at $29 a month for proper uptime monitoring with multiple regions. The free tier checks every 3 minutes from one location, which is not real monitoring.
Sentry’s Team plan is $26 a month. You can run on the free tier if you stay under 5k errors, but a buggy inherited codebase will burn through 5k in a week.
Customer support
The cheap option is forwarding hello@yourdomain to your inbox. The grown up option is Plain at $35 a month or Help Scout at $25 per user per month. Skip this until you have actual customers asking for help. Most acquisitions do not need it for the first six months.
The non-monthly costs
These are the ones nobody mentions in the listing.
The original Terms of Service and Privacy Policy were written by the previous founder, probably copy pasted from a generator. If the product handles any user data, you want a lawyer to look at it. Budget $300 to $800 once.
If you operate through an LLC, your accountant will charge you something like $200 to $500 a year extra to file for the new entity or new revenue line.
Cyber liability insurance for a B2B SaaS that touches customer data starts around $40 a month for the smallest policies. Most solo buyers skip this until they have their first enterprise customer ask for it. Then they panic and pay double for rush underwriting.
What it actually adds up to
For a small inherited SaaS with under 100 users, the realistic floor is $50 to $200 a month just to keep it running. For something with paid users and any AI in the loop, $300 to $700 a month is normal.
That is $600 to $8,400 a year of carrying cost before you do any work.
How to bring the number down
The single biggest lever is stack consolidation. Cloudflare can do hosting, DNS, R2 storage, KV, D1, and email routing for one bill. Migrating an inherited Vercel plus Supabase plus Postmark stack onto Cloudflare can cut the monthly run rate in half. It is a real weekend of work, but it pays for itself in the first three months.
The second lever is cancelling things. Most inherited projects have at least one paid service the new owner does not need. The previous founder was paying $29 a month for a feature flagging tool used twice. Kill it on day one.
The third lever is downgrading. PostHog Cloud often fits inside the free tier once you turn off session recording. Sentry can run on the free tier if you fix the noisy errors first.
The takeaway
When you are pricing an acquisition, factor 12 months of operating costs into your offer as a baseline, not a bonus. If the asking price is $3k and the carry is $200 a month, you are really paying $5,400 in year one. Sometimes that is still a great deal. Sometimes it is not.
The buyers who do well on Failedups are the ones who price the carry into their offer before they wire the money, not after.
If you want to see what is for sale right now, browse active listings. If you want a sharper handle on what to actually pay for one, read how to value a stalled startup.