Lets start with two words - pawn shop. I have a variable speed black and decker that I bought for $20 at a pawn shop about 5 years ago. It has variable orbits, but the feature I like best is that I can unlock the blade from its straight ahead orientation and pivot it in a circle. this lets me cut far closer to edges (I use it to cut out sinks in countertops, where the backsplash gets in the way). The advantage of pawn shops is that the difference between a great saw and a cheap one isn't always readily apparent. Different shops do better at knowing the difference than others, so shop around and you'll find the shops that don't have a clue.

As already stated, think about how much you'll use it, and buy accordingly.