I've been looking at the one from Harbor Freight. I don't use it daily so that might be good enough for me.
Craftsman C3 Heavy* Duty 1/2" Impact Driver, conservatively rated for 300ftlb, does pretty much any automotive bolt.... furthermore, C3 battery packs are useful to have, for example I grabbed up a C3 open box drill for $24 the other day at Sears. They had other such stuff too.
Harbor Freight, prolly not a good idea. Not known for safety power or reliability... and the whole point of keeping a heavyish duty cordless impact is that if it keeps you breaker bar shelved and avoids you even one minor injury or pulled muscle, it has paid for itself many times over
Saves your knuckles. Saves your back. Saves tons of time... Maybe more, but aint that enough already for a hundred bucks and change???
Its really not something you can afford to skip or skimp on if youve ever found yourself picking up a breaker bar or laying into a wrench
PS for craftsman at least, "heavy duty" denotes a distinct separate model....regular one is kinda half-assed, judging by the features and rated power.