as wookie said porbally the best crawler on budget would be a txt pretty much the only upgrade the need out of the box is oil shocks as the kit comes with friction shocks.

Crawling can be really expensive to get into if you aren't good with building.

Don't forget if you decide to get a kit you will need to purchase a esc,motors,servo(s) and a radio.

Most People use a Novak Super Rooster For Crawling novak stated a 15 dual motor limit but I'm running dual 14t in my racer clod with no problem.

For motors I use magnetic mayhems with a 22t motors made by kyosho they have plenty of torque for what I do.

Allot of serious crawlers use 4WS witch in most cases require 2 servo you want a servo with atleast 100oz of torque to turn the big wheels(believe me when you open your kit you will see what I mean).