I'd say that not the amount of time spent on the development of the software is the crucial question but the expected earnings. If the idea is really novel or promising and the expected revenue huge than an investor is paying for the idea and probably the team and not for the work done in these three months. If the team consists of gifted inviduals and a great idea than it seems to me not to utopian to accept only a very high sum because it is rather rare to have a very promising idea and gifted people together.
I would have to agree, the problem is when you have to self measure a potential projects earnings before it comes into a large circulation.
I think it would be very easy to over/under estimate a projects worth, personally I would think that a percentage of profits over a certain period of time plus a smaller lump sum would be ideal for me.
I am a little new to this game but I would assume it would also increase my motivation to see a project come to fruition if I had a more longterm stake in it.
