The price will depend on which model you go with a SA, SE, or SE V2. I built my V2 last July and bought all of my parts from my LHS this is how mine broke down. My initial startup cost was around $1250 with a radio and tools without a charger/balancer and spare parts. Don't forget to budget in $$$ for the spare parts that you WILL quickly need.

T-Rex 450 SE V2 Black Carbon Fiber with Carbon Blades $429 + tax
Spektrum DX7/AR6100 $300 + tax (You have a radio but will need another receiver)
Hitech HS-65MG servos $35 X3 $105 + tax
Futaba Gy401 Gyro $125 + tax
Futaba S9650 Digital Tail Servo $50 + Tax
Flight Power Evo25 3S 2170mah Lipos $70 each. I get 6 minutes of fligt time per flight. I have 4 of these and 1 Thunder Power 3S 2070

You will also need some misc. tools like a pitch guage, ball link pliers, and a set of digital calipers to setup the heli properly.

I would also suggest a good sim if you don't already have one. A good sim will save you a ton of money when learing how to fly your first heli.

You can get into a SE setup for about $60 less than the SE V2 and a SA (all plastic head and tail) setup for around $200 less.

Good luck and have fun.