Under the laws of most of the United States – Alaska may be an exception – it is illegal to sell wild game. Any website or mail-order company purporting to offer “wild game” – animals taken from the wild – in the USA is either breaking the law or making a fraudulent claim. The situation may be different in the UK or other countries.
On occasion, however, when hunters fail to pick up their items, wild game is offered for sale (illegally) by processors stuck with the costs of butchering the carcass. Other than that, the best way to “purchase” wild game in the USA is by buying a bow, rifle, or shotgun and a hunting license, and spending some time in the field. Alternately, by making friends with hunters, one may usually obtain meat by barter. Hunters are very often willing to share their catch with someone who offers to do the cooking, even more likely if you also dress the carcass. Be sure that deer and similar large mammals were properly field-dressed, and that birds and small mammals were immediately put on ice. Learn to recognize signs of disease and avoid anything that seems parasite-ridden or otherwise “off”.
A legal-and culinarily superior-alternative to wild game is domestic ranched or farmed game. This “game” meat comes from managed herds and is inspected for safety and quality by the USDA. Upscale supermarkets often carry bison, duck and quail, and specialty butchers and even some supermarket meat counters should be able to obtain the game meats you are looking for given enough advance notice. As an alternative, anything from the common venison, elk, duck, and pheasant to oddities like boar, yak, and rattlesnake is available over the Internet from the same sources used by restaurants. D’Artagnan, Fossil Farms, ExoticMeats.com, and Venison America are four of the largest suppliers of game meat in the USA; using your favorite search engine to find pages about “game meat” or “venison” will turn up others.
Keep in mind that, similar to the distinction between grass-fed Western beef and corn-fed Midwestern beef, ranched game will nearly always be slightly tougher and fuller flavored than the farmed equivalent. Neither, however, will approach the strong flavor of true wild game; both will be meatier and easier to cook without drying out. Game purchased at a butcher or supermarket should be selected using the same critera as beef and chicken; frozen game purchased over the Internet should be shipped in dry ice, preferably vacuum-packed to ensure freshness and avoid freezer burn.