coolers are not that expenisve. i would not recommend running ur CPU at any higher temp than u need to. OC on stock cooler is not a good idea in my opinion. u can do it, yes, but 50*C+ is more than most good coolers will ever let ur CPU reach. i wouldnt do that for a long period of time, like if u OC and play games, you may reduce the life of ur CPU, which is definately more expensive than a CPU cooler.
i have the Xigmetek Dark Knight
. it is big (but fits in my ATX mid tower), not too heavy, really pretty looking and really worth the money. it has the mounting plate that goes behind the motherboard included. this helps brace the board and will prevent bending/cracking over long periods of time. my e5200 @ stock 2.5ghz runs at 22*C idle, 29*C load. the cooler hasnt broken 1500 RPMs and its max is 2200. i plan on running it at 3.2ghz or so. best yet, it costs. it costs $45. dont be intimidated by installing a cooler, its easy adn the dark knight was my first CPU cooler. after i got the HSF ready, it was a 5 min job and has a really sturdy mounting.
there are also cheaper coolers that do well starts at $25, but they dont ahve the extra mounting hardware and may not be of the same quality.
if u do get teh dark knight or another HDT (heatpipe direct touch), make sure u look up some guids on how to install them. try to fill the groves between the pipes with thermal compund and then instal like normal from there