Build a SaaS MVP with AI: cost, timeline and stack (2026)

At a glance

• A real SaaS MVP is in production with accounts, multi-tenant isolation, billing, and at least one value-driving feature — not a prototype.
• Cost: a full SaaS MVP from €6,900 HT, or a feature to add to an existing product from 490 € HT. Timeline: 4-6 weeks for an MVP, 2-4 weeks for a feature.
• The most underestimated cost: multi-tenant isolation (RLS) and billing. These are rarely "the core" but are non-negotiable.
• Assembling proven building blocks (auth, RAG, signature, billing) dramatically reduces timeline and risk compared to building everything from scratch.

The problem, concretely

"We want to test our idea fast and cheap." Good instinct, but an MVP without isolated accounts and billing is not testable in real conditions: it is a demo. The common mistake is coding everything from scratch, including the plumbing (auth, multi-tenant, billing) that does not differentiate you but takes weeks.

What a SaaS MVP actually contains

• Authentication + multi-tenant: each client isolated. In practice, well-tested Row Level Security (see our multi-tenant RAG isolation article).
• The core feature: the product promise.
• Billing/subscriptions, and a minimum of administration.

What drives cost and timeline

The scope of the core feature, the integrations, and above all: starting from zero or reusing proven building blocks. The plumbing (auth, multi-tenant, billing, document generation, RAG) is the same from one SaaS to another, and this is exactly what eats the budget when you rewrite it.

Accelerating without cutting quality

Reusing building blocks is not "cutting corners": it is the opposite. Code already proven in production is safer than a core rewritten in a hurry. Customization focuses on what differentiates you (your core feature), not on the plumbing. By assembling features extracted from BeForBuild.com around your idea, you get a solid MVP, in production, at a controlled cost — not a throwaway prototype.

Start with a free 30-minute audit: Freelance AI agent developer or Freelance Supabase developer, fixed price from 490 € HT.

Sources

• Supabase · Row Level Security
• Supabase pricing (MVP operating cost)