I have looked into FCC testing myself, only 3-5k if you've got spare change.
Linx Technologies has got some great material on the subject.

After looking through LINX technologies website and making my list of (should have learned this in college EE Communications) questions I called LINX to ask the same kinds of questions you have been asking. Everything posted so far sounds in line with what I was told my the antenna factory/ linx rf modules guys.

One thing to consider is what kind of data are you sending?

Continuous? Intermittent?

900Mhz alows for continuous data but 433-434 Mhz does not. If you are just using rf modules for hobby work or you don't care about FCC rules (you obviously do) you can just send continuous data in a loop at lower freq with lower cost modules from Linx.

Also most of the rf modules require line of sight applications to get the full range advertised by the companies making them.

I admit that I have limited knowledge as I have only been designing with rf for a few years now. So far I have used the LINX KH2-xxx-xx & LR-xxx-xx modules both at 433Mhz. I was cheap and did not buy the prebuilt development boards. So to save my time/money/heartache from a wasted prototype.... I called LINX with LOTS of questions about laying out my ground planes, rp coax connections, etc before having my PCB's made. Taking my time and calling their tech support was worth it. I

totally recommend reading all you can from their FCC dowloads, rf for tech challenged, antenna theory manuals and give em a call. The last guy I spoke with (at linx) was an rf communications vet of 25 years in IRAN, IRAQ, CANADA with military and non military rf design experience. They know their stuff! Hope this helps!