+1 for tvfool.com
Also, we have an antenna that looks very similar to the Costco/Amazon one linked above and it works great. We get 4 or 5 HD channels but some people get many more -- it totally depends on your location, elevation, obstructions nearby, etc. Picked it up at a local electronics shop (like Best Buy, Future Shop, Radio Shack, The Source, etc)
One day I'd like to get a rooftop one for a stronger signal pickup, but not right now .. too much $$$. Hair is on fire, ATM (sigh).
Forgot to add: start out by trying the cheapest one. If it doesn't work, after moving it around to multiple locations, return it and try the next level up. We were satisfied with the signal from a $20 device, even though there were $80 ones available. YMMV