A good comp crawler setup will be on moa axles (motor on axle, 2 motors) like bully's, bergs, xr10's or a converted losi CC.
You would need two motors, integy's would work to get you started...$20ish each.
A good esc, Sidewinder, Mamba, FXR or Holmes....$80-$120ish.
BEC....$20ish
High torque servo, ATLEAST 300 oz....$80 on up.
A dig switch from Punk rc....$70-80
A 3ch radio....$100 on up.
3s lipos.....
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That would get you started on any of those setups.
But if you want really good setups, you really gotta spend some coin.
What I'm running on my current comper (electronics wise)
two Team Brood 45t motors....$120
two HH ESC's.....$200
BEC.....$20ish
Hitec 486oz servo...$1??? I forget how much is was
Futaba 4pk radio ......$500ish
4s lipo.......
Thats about what it takes now days to have a really comptetive rig depending on who you comp with. All the guys in my club are all on MOA axles also with atleast the setup I listed first and some with the same setup basically as me as far as handwounds and very high end stuff.