If you're dead set on a RRA, check out
http://www.ar15sales.com/
They'll probably have to order it since I doubt they will have a rifle in the configuration you want in stock, but they have the best prices on new RRA's that I've seen.
I bought one from them last year and transferred it through Quinby's in Dublin. AR15sales already had Quinby's FFL on file. I just called Quniby's and told them what I wanted to do and they said they would call me when my rifle arrived. It took about 6 weeks for the rifle to come in since it had to be ordered. The ordering and transfer process thru AR15sales and Quniby's was totally painless and I would definitely do it that way again if I was in the market for another AR.