Every time the roommate and I go on vacation, he gets a magnet and I get a "I heart (whatever city/state/country we visit)". These are our souvenirs when we go on trips. Realizing we never got any during our past Vegas trips, we decided to stop by Magnet Max.
They mainly have magnets, but also offer other souvenirs, such as clothing, shot glasses, mugs, etc. We ended up getting 3 magnets for $12, but you can also get one for $4.99. They had a white I heart Vegas shirt for super cheap (like $6-8?), but I had already bought a black one from another souvenir store. Plus, I believe if you buy 3 magnets, they offer an additional item (like a shirt, water bottle, etc) for somewhere around $3-$5.
For a great deal on souvenirs, this is the place!