Thank you for writing out this response. I knew that I should not be worried about somebody stealing my idea, that's why I asked about selling the MVP, not the idea. But you are right: Even though I believe that the MVP is well written, I am effectively competing with the cheapest outsourcing shop.
Agreed, and I'd be careful with thinking about it as "well written" in this context. An abstract notion of quality doesn't matter nearly as much as whether it suits the person taking over the code base. If you're selling to another developer, then they have to have similar language and framework tastes. If you're selling to a non-technical person, then it's more about whether they can find somebody who can more efficiently work with your code than build from scratch. So in a strictly commercial sense, a mediocre PHP site can be more valuable that a very smartly constructed Erlang site.