"I should bite my tongue"

Really?

In those situations I feel that it's completely appropriate to tell them "no thanks" and move on to clients who are actually willing to do business.

Dear Steve,
While I have gone something similar, it does not hurt to point out a resource/link. Sooner or later people do need support and feature-development. There would be people who just don't know and just might want to know of softwares to take for a test-ride (or the equivalent of that). I do see a genuine need at times to figure out an equivalent need of softwares in FOSS which might not be mainstream and I have yet to find some good quality site for doing that.

I have to yet a combination of google,debtags,aptitude search and wnpp.debian.net to figure out the software I am looking for and sometimes that also doesn't work and this is when I'm okish with Debian and FOSS.