I was first introduced to this concept by a colleague who was going to serve customers manually instead of us programmers automating it. I said he was going to have a major issue when lots of people sign up. He replied "That is definitely a problem I want to have, I hope I get completely overloaded, because then we have the money to automate it".
I guess it is related to Paul Grahams "do things that don't scale", but "problem I want to have" is broader.
Since then I always evaluate if certain problems are the ones I want to have, because then I know I can postpone them.
I think you are missing the point that in this case you _don't_ have the money.
And they don't sign.
And it turns out what you worked on for them isn't something other customers of their size really quite want. But if you jump through these hoops...
If they are your customer, there's no more hoops to jump through.
I don't see the problem you are describing here.
You don't renegotiate from $49 to $60,000...
Better make sure they don't then so you won't have to support a large company that signed up because of the low price.