If you have a problem with the roads where you're at being so bad that you're prematurely breaking the OEM shocks, you certainly do not want to go with a cheap coilover. I would go so far as to completely advise against pretty much any coilover in that situation.
Your cheapest possible option is to order the two blown shocks, OEM, from some place online and install it yourself (check ECS, on sale right now). If you want a durability upgrade I'd go with a set of Bilstein HDs.
You also don't want to run a mismatched set. So don't buy aftermarket Konis for the rear and run stock up front.