Reloading for the 10mm isn't particularly hard or expensive. The only components that are cartridge-specific are the cases as 10mm uses .400-diameter bullets, large pistol primers, and relatively common powders. Flat-nosed bullets should be quite easy to find as they're quite popular for the .40 S&W cartridge (180grn is also standard weight for both cartridges) and 200grn bullets probably won't be hard to get either should you want to use them.
As far as factory ammo goes, it is more expensive and you probably won't find it at Wal-Mart (though one local Wal-Mart does occasionally have a box or two of Winchester Silvertips in stock), but the situation isn't as bad as many make it out to be. Most decent gun shops in my area will have either Remington or CCI Blazer FMJ's in stock and either Federal Hydra-Shok or Winchester Silvertip JHP's. Typically, 10mm FMJ's will cost $25-30 for 50 rounds making it comparable to .357 Magnum ammo, and better prices can be found by going mail-order (Georgia Arms remanufactured seems to be about the cheapest).
http://georgia-arms.com/10mm-1.aspx
Be advised, however, that most commercial 10mm ammo is loaded very mild (about like a warm .40 S&W). Winchester Silvertips are the only big-name commercial loads that are noticeably more powerful, and even they aren't really up to what the cartridge is capable of. If you really want to realize the 10mm's full potential, you're going to have to get ammo from either Double Tap or Buffalo Bore or load it yourself.