Back in 2004, 2 of my friends and I spent 4 nights in Vegas at the beginning of June (Thursday-Sunday). Because the room prices were higher at the weekend than during the week, we couldn't afford to stay in the same hotel every night, so we spent Thursday night at Circus Circus, Friday and Saturday nights at Lady Luck (downtown) and Sunday night at the Excalibur - the costs were fairly reasonable that way and we got to experience 3 different hotels (Excalibur was my favourite).
We were on a budget of between $70 and $120 per room (all of us were in one room, so that was $23-$40 each).