I was just out in Arizona 3 weeks ago Jesse. Nice place, and definitely a bit warmer than your neck of the woods...

My parents live in Scottsdale though (near Phoenix), so I'm not too familiar with Yuma really. One of our members, DaBigKahuna, recently moved out there - maybe you should drop him a line and see if he's got any good tips or sites to see for ya'.
Just hop onto Google and figure out what the zip code is for Yuma, then hop onto Walmart.com, Target.com, etc. and do a search for stores in the area. I'm sure there'd be a few.
I think 'Scum has a huge, very active, Arizona finds thread as well - so you might want to check in with those guys as well. Bummer it's not a little closer, or I'd try to come by and pay you a visit. But as it is, I'm about 7 hours away...
Have fun! You ever been to the States before?