a descent setup can be done for $5-600 with the stuff rollin mentioned.
$230ish for a artr
$100ish for sidewinder and
bec
$30-100+ for a servo, depending on how nice you want
$20 for a motor
$25-$300 for a tx/rx, just depends on what you want to use.
$25+ for battery
its kinda hard to give exact prices on radios and batteries, if you went lipo that could start around $30 and go way up, or nimh, wich would be pretty cheap for some nice saddle packs....if the axial artr is something you might want to do, maybe start out with it and then go from there, if possible try to get a sidewinder or mamba max and a cc
bec for sure then move on. a hitech 645mg servo can be had for around $30 bucks wich will work ok or you can spend way more and get a servo putting down over 400+ tq. the hobbico cs170 is 333oz of tq and get be had for $80 wich is a steal...the radio is all up to you, you can run a super cheap am radio and can find them for like $15 shipped alot of the time! but if you think you will end up wanting to run dig then you will need a 3 channel with 3rd position switch radio, wich you can find modded tq3's for cheap sometimes or spend the money and get a spektrum dx3 or 3r and have all the settings you need for dig....
heres something that might help you out, ckrc does package deals. heres a axial kit and ck includes all electronics with it....it will need assembly, and thats complete assembly by the way, axles, trans, everything has to be assembled, or for $20 more they make the same deal but with a axial artr...
http://www.ckrccrawlers.com/shop/index.php?main_page=product_info&cPath=5&products_id=674
click the "here" where it says to upgrade