Understanding the real cost curve of vibe-coded apps from MVP to production

The rental web is catching up to SaaS: bolt-together no-code frameworks like Lovable and Bolt promise a working UI in minutes and a fast path to MVP. The pricing looks honest—pay for what you use, stop when you stop. This lands well in early demos and hackathons. Here’s the catch: real apps grow, and subscriptions and credit models tilt the cost curve dramatically as “sandbox” usage becomes production. When you own your kit, you pay once, own the code, and the meter stops.

Most teams keep paying for the privilege of not owning the base—indefinitely.

Let’s walk through what you actually pay as usage scales, hard numbers, then where owning the kit breaks the loop.

Sandboxes are cheap — until you scale

Spin up a “workspace” or “app” on any payg tool. $10/mo covers a small app, some database rows, and a few thousand component renders. It feels like a win compared to the up-front cost and unknown effort to write your own stack.

This is exactly what breaks down.

Every metric you care about—seats, records, requests, storage, function calls—grows with your user base, features, or just being alive for months.

• 1,000 signups? That’s a plan bump.
• Overage charges on usage spikes, even when revenue didn’t spike.
• Want branding removed? That’s $39/mo instead of $9.

What felt like a cup of coffee a month compounds, and you never stop paying to hold your code hostage.

The numbers: a real scenario

Let’s model an app—a fitness tracker that launches on a Bolt-style platform. MVP supports 2,000 monthly active users, with a basic set of screens, modest logic, and some scheduled jobs.

• Sandbox: starter at $12/mo, capped to 500 records, single admin.
• Growth: bump to $39/mo for 3,000 records, +$15/mo for scheduled tasks, +$9/seat for guest trainers.
• Storage: 250MB included, +$5/mo per GB if users upload images or files.
• Function: 10,000 invocations included, then $5 for each 25k calls.

In three months:

$39 base
+ $15 jobs
+ (5 trainers × $9)
+ $10 extra storage
+ $10 extra function invocations 
= $119/mo

Annualized: $1,428 just to keep the doors open—no codebase portability, no local dev, no change of infra.

The “cheap” period ends as soon as you have a feature or user graph that grows.

The unit economics don’t trend in your favor

Sandbox platforms charge per feature and usage. You keep paying for:

• Each additional record or row (users, events, invoices), not just storage
• User seats (we see 2× headcount tax on a growing ops team)
• Function execution (every API call, even for scheduled or periodic jobs)
• Non-branding
• Moving off their infra (a “download” often costs extra or is blocked at scale)

A single spike—say, a PR mention—can cost 10× your expected run rate that month.

You “own” nothing: code, infra, or price stability.

What your $99 buys when you own the kit

Contrast: buy a kit like OTF’s full-stack Fitness or SaaS for $99, you pull the repo and own:

• Codebase: React/Expo + Hono + Postgres, editable end-to-end
• Design system: ~200 fully themed components for web + native (@otfdashkit/ui, @otfdashkit/ui-native)
• Auth, payment, jobs, infra as infra—change them at will
• Real migrations and seeds you control (no row count lock-in)
• All source, invested in by contributors (not a walled garden)
• One-time cost: $99. All-in. Everything else is open-source, stays free (MIT).

Real cost: $99 + whatever infra you pick (could be $0/mo on a light Postgres + Vercel hobby plan). Years out, the marginal cost is still zero.

enable: own the output, swap the infra, and pay once.

The lesson here is simple: buy and hold the base. When the work is real, rent stalls and owning compounds.

Originally published at otf-kit.dev — full-stack kits your AI coding agent can actually ship to production. See the kits →