I just posted this in the thyroid forum too, but I wanted to make sure you saw it.
The test is not $100. It's $400+ and I would wait on it until they have treatment option. Currently most doctors are not treating for XMRV. I know many people already who are testing positive for this and who are just sitting on the fence with their piece of paper saying they have a retrovirus and there is nothing that can be done until the Whittemore Peterson Int. is vindicated and the CDC has their buy in.
Currently there is some new studies being done to determine if a new retrovirus that was recently brought to light late last year is the cause of CFS. It's called XMRV. HIV is also considered a retrovirus. If I were you I would Google XMRV when you have some time.
The virus is still being researched at this point, so it has not been cleared as the definitive cause for CFS (or even FMS), but it does show some promise. There is a blood test for the virus, but I would not recommend getting it at this time because scientist don't really know what it means at this point and doctors don't have a treatment either. You can learn more about the organization who discovered the virus by going to this website:
http://wpinstitute.org/xmrv/index.html
If I were you I would wait on the test and see how thing evolve. There were a couple of studies that have been performed since the initial research proved the correlation and they were contrary to the first findings. I think there are a lot of politics going on and the research population samples may have been different in each study. They didn't mimic the original research from what I understand. Anyhow, I hope I wasn't too technical. I hope this helps you. Feel free to ask questions.
-Dusty