I've heard good arguments for both. I have a tendency to research down to the ground anything I buy, and never buy anything on impulse. As a result, I typically buy the top-shelf gear even if I have to save an extra month to get it; often you do get what you pay for. Reliability, usability, and overall quality are seldom cheap. If you're going to trust your life to it, you may not want the best bargain.
My brother takes the opposite approach. He buys cheap gear more often than not. It may not be the highest quality, or it may break sooner than my gear, but he has twice the number of guns and gear that I have. He points out he can buy 5 Barska red dots for the price of one Aimpoint. If they work, who cares if one breaks? He's got 4 more to replace it.

