Just buy one that you can get replacement blades for locally. The blades on those things wear out fast, whichever brand you buy. (although I have never used the one t100 posted a link to).
HF has them for $2 on sale, results are mixed, due I suspect to some good and some not so good, but if $10 worth of them will do all the spot welds you need done this lifetime, why pay more?