Excuse my ignorance on the currency, it makes it hard to figure out what you are actually spending, but I think the Buy It Now price is $575 and if so, that is a fair price! It's a high cost but a fair price for all the goodies! So for less than $600 you could have everything in the auction... or:
Venom Creeper kit or Axial AX10 kit - $150
Full Spectrum Radio $80
Motor and Speed Control $115
Battery $50 +/-
Charger $50 +/-
Hi Torque Steering Servo $50 +/- (x2?)
$550 = $25 difference
Honestly, you have to ask yourself what you think you would provide more fun within your area and terrain. If you have a bunch of places full of boulders a Venom would be very entertaining but a scaler would need to go elsewhere, most likely. The Tamiya is going to be heavy and it will struggle to pull itself up walls and such... basically, the Tamiya is set up to be a trail rig, the tires that are on it are suited to trails, the weight of the chassis keeps it away from steep climbs, the body has lights on it which makes night trail runs really fun.
The Venom or Axial is much lighter, the trans of the Axial is tiny therefore minimizing extra weight up high. The Venom or Axial will scale things that would blow your mind partially becuase of the softer tires but mainly becuase of low weight. The more you gear up a crawler to be a scaler or a bling king the less performance you get out of it. Have fun!