You should sell the ps3, since you love halo ( Thats y i sold my ps2 and bought an xbox 360) 
I find that x-box has much better games on it. 
Also, go check out E-bay, or something like that. 
I got an x-box 360 and 1 ODST for $150 Second hand. 
So yeah, in short: 
1. sell ps3 
2. Buy x-box second hand 
3. PLAY HALO 4!!!!!!!!!!!!!!!! 
p.s. Don't sell it to EB games, you'll get like 1/5 of the price of the ps3. 
You should sell it on E-bay you'll get what it's worth there.