I bought a 6600 too, and I didn't really negotiate either. I bought it during the local quilt show so they already had a "special price" on it.
I may have gotten a better deal elsewhere if I really shopped around since I live in an expensive area, but I figured any extra costs wouldn't really be huge and are worth it to help keep the local dealer's doors open for when I have problems or questions.
Zero regrets. Love my machine and adore my dealer!