Rotny,
If they require an educational evaluation, they want to verufy if your basic education is comensurate to the requirements of your filing category (EB1, EB3 etc.). There are a lot of independent bodies who do this evaluation for a small fee. I had recieved such an RFE, my lawyer responded back with a evaluation which he conducted from an independent source. Sorry, I have no specific info about the company he used for the same.
-Savant