I've not used this license, nor do I know where it came from, but it could be the one for you. It's called the Developer Source License
. It allows non-commercial and "tiny-startups" to use your program for free, and hack with it. But they can't sell on the hacked version. I think it's a pretty groovy license for people like yourselves who want to give something back to the none-profit community, but still need to feed your families.
Commercial entities must purchase the software, and then they can hack with it, I think. Either way, the Resin JSP Server uses it, so check it out there.