Is it worth 10k to you to sell? Do you think they'd pay more? Is this an aqui-hire? Are they bringing you on? Have you thought about getting angel investors to maybe see this through and help you grow it?
Yes. That's the perfect price.
> Do you think they'd pay more?
Probably not, but I wouldn't want to sell it even if they said $20k.
> Is this an aqui-hire? Are they bringing you on?
No.
> Have you thought about getting angel investors to maybe see this through and help you grow it?
The project is so simple that I don't believe anyone would ever want to invest in it.
The perfect price for a seller is the maximum price a buyer is willing to pay.
If the former is greater than the latter, no perfect price exists.
There is in reality such a thing as dis-utility, which can mean any price over some $xx,xxx is actually less valuable due to marginal utility of each additional dollar actually being negative.
The marginal utility is really the sum of the economic utility of the dollar and the emotional utility, you can in fact have a negative emotional utility that is greater than the strictly economic utility of the dollar.
And to be honest, I don't think I'd ever have that feeling, but it can be a realistic phenomenon.
Don't automatically assume you have to accept their terms and negotiate on price. You can ask for anything you want. You don't get what you don't ask for. If it's a publicly traded company why not ask for stock? A stock deal might be more valuable than a cash deal. Something to consider.