You can make jerkey with store bought meat. Hell, while your there have them slice it for you, just be sure to tell them your making jerkey with it so they slice it nice and thin.
Actually, I make jerkey with store bought meat all the time. Really simple actually..you can even use ground beef if you want. Just be sure to use like 93/7 or something close to it. You don't want too fat of beef/meat or it will be really greasy..also if its too lean it will be dry and crumbly.
If you going to make deer jerkey add in some 90/10 beef with it. 1 lb to every 5 lbs of venison.
I use a dehydrator to make my jerkey, but you can use an oven as well. other than that all you need is some cure and your spices which i usually buy in bulk online.