Camera lenses are expensive. However, investing in a few good ones is probably the best thing that anybody who wants to take great photos has to do. But back to the shot glasses, these are probably the cutest little 24-105mm shot glasses we've ever seen (the shot glasses don't really zoom).
For the shutterbug, Photojojo's set of three camera lens shot glass would make a great gift. At $18 for the set, it's not extremely expensive and the little raised nobs and dials will surely bring authenticity to the glass.
Nikon loyalists are out of luck. There isn't a shot glass to win your love, yet.