It's because the nitro has a clutch. When your crawling, you need direct power and holding power. With a nitro, you have to spool up before the clutch engages, and while you're sppoling you would have already fallen backwards off the rocks, lost the competition, and your rig fell into the grand canyon. With electric, there isn't a power band, It's full torque from the slightest pull of the trigger, which is what provides the instantaneous response and holding power for crawling. Of course, there is a much more scientific answer, but I kinda dumbed it down to make it easy to explain.
You're not going to find a cheaper crawler than the Axial AX-10 rock racer that smaxxin mentioned. The other rigs would take more than your budget just to begin to get the crawling, where as the axial is ready to go and can be picked up new for $250, and used for your budget and better occasionally. If you're thinking of getting into crawling, just save your money for a few more weeks and buy the axial. I almost got a TXT-1 because it was for a good deal, and then realized that I was going to get something that was not what I wanted at all, so I waited for about 5 days until I had the extra hundred bucks and bought the axial kit, which I am absolutely in love with.
Another option would be the wheely king 4WD, but you will spend just as much on it as the axial, and then have to spend more to get it crawling.
:surrender:bow:
