The way they pay local scooter mechanics, a couple cases of beer is probably half a months salary. 

Quality costs, always has always will.  If you're flying IMAC or big airplanes I wouldn't think you'd ever look at a 100 dollar engine.  If you're converting weedeaters from peoples garbage into flying engines and slapping them on sport planes, that's a different story.

Cheap is relative.  a couple bucks a day is cheap although in one shot its 700 bucks.  If you fly 10 times a year it's 70 bucks a day.  IF you fly 10 times a year and your engine ruins one or two of those days, 70 bucks a day is CHEAP.

Analyze YOUR usage and spend your money wisely.