You can spend some good money on any Rc car. I have an HPI Savage that's got an extended chassis, widened axles and arms, 3 speed tranny, 3hp motor, and a bunch more to it. Last time I added the total, I was up to about $1800 counting the $400 for the truck when it first came out.
Before you purchase it, check out this site: www.rccrawler.com/
. It has allot of useful info on the AX-10.
It doesn't matter how new you are to it. If you have the patience and don't mind putting it together, then you will have an awesome rig out of the box if you get the kit. The RTR and ARTR are nice also. They just don't come with the upgraded parts that the KIT version does.