#1
So i know that ideally i'd need to cover all corners with bass traps but currently i can only afford to get two, so where would be the best place to put them for mixing, so for example in the corners behind the monitors or in front?
#2
In the corners to your front right/left when facing the mixing board/monitors.

If you're buying from retail, you're getting ripped off. You're MUCH better off building your own, it works out to about $15-30 per trap depending on materials. There are a million threads on this forum (and others) that detail the process. I'd recommend spending some time reading up on that.
Telecaster - SG - Jaguar
Princeton Reverb, Extra Reverb
P-Bass - Mustang Bass
Apogee Duet 2 - Ableton Suite