I'm sure you've already got something in mind, but here are some starting out suggestions; just some things that are inexpensive and forgiving when starting out:
1.) Pork - Picnic Shoulder Roast: It may take nearly 15 hours to smoke, but you can pick one up for about 10 bucks and do several things with it. Pulled for sammies, chili, bbq spegetti, or bbq pizza; it's very verstile. It is also very hard to screw up, so it works well for a starter.
2.) Fatty - If you don't have time for pulled pork, try a fatty. Take a Jimmy Dean sausage chub and rub it with a good pork rub. Smoke for at couple of hours at 225 until it reaches 165 internal. When you get the hang of it, you can fill the fatties with all kinds of things. I like to fill mine with green peppers, onions, and cheese. Slice yourself some thick pieces with some fresh biscuits, mayo, and tomatoes.
3.) Beef Ribs - OK, not really good for a starter, but still cheaper than a rack of pork ribs. Here in Sedalia, you can get a good sized rack for $6 bucks. You can get your rib fix cheap!
There are tons of other things you can get started with. Take a look around and ask many questions.
Hope this helps.
