Hammer's gloves look like electrical safety gloves – very thick rubber.  Try Mcmaster-Carr (mcmaster.com) part number 5333t79 (11″ cuff).  They're a bit pricey, since they're designed to save lives (about $50).

I have a pair of Leather gloves that I got at the Michigan Renessance Festival that are very close. They're Black leather gloves, with a suede insert on the side (you can see this best in the shot of Captain Hammer near the beginning of act 3). the only problems is that on mine the suede is red (black is available), there's additional pieces of suede on the back end of the gloves as decoration (removeable, but a pain) and there isn't a buckle at the wrist (this could be added). Unfortunatly I don't remember the name of the dealer, but MRF starts for the year again this weekend so I'll see if they're there and get the name.

Overall the seams in the leather and the overall weight of the leather (that's the thickness for you non-leatherworkers out there) looks spot on. it shouldn't be hard to get the dealer to make a pair without the extra suede (as a leatherworker I love it when people are willing to pay the same for less work). The buckles might be hard, but I only know a very few leatherworkers that won't modify a pattern for a few bucks extra. I'll try and post again when I find the name.

These batman gauntlets are also fairly close if you remove the "spurs" with a sharp knife.  All that are missing are the buckles.
They're also fairly inexpensive (~$14), and can be found at most halloween shops.

http://www.amazon.com/Adult-Batman-Gloves-Std/dp/B000H8KIAM/ref=sr_1_13?ie=UTF8&s=apparel&qid=1225205776&sr=1-13

in a pinch, a pair of Darth Vader gloves ($15) worked.

sadly couldnt find anything in the bike shops i tried in my area and these worked out!