I bought a new XS3 75Hz on eBay a couple months ago for under $200 from a dealer. Used the JR590 servo as an upgrade on an RTR for my friends to play with and sold the JR270 servo to someone that needed a cheap replacement.
The XS3 75Hz unit is great. 30 channels to select from. RX300 receiver appears a tad bit heavy; but, my XXX-S cars are still at the minimum weight. Has the useful "bells and whistles" of the more expensive units; however, I now tend run many settings at "straight up" stock.
Get the 75Hz as opposed to the 27Hz unit.
Consider the optional recharger for the radio with NICAD or NIMH batteries and you have a terrific setup.