SPL METER? ATI OR RADIO SHACK

I am looking for an SPL meter for speaker placement and room acoustic information. I know radio shack makes one, and I have seen an ATI SLM 100 advertised on the net and
Music Direct also sells it. Does anybody have a personal experience with either. I am looking to spend within the $100.00 range, but of course looking for one that is reasonably accurate. All opinions would be welcome