For those interested in trying comp BBQ but getting discouraged by this thread, realize that most/all of the cost estimates on here are for sanctioned Pro contests.There are other less expensive options like KCBS Backyard events, unsanctioned events, and rib cookoffs.
We are cooking a Chicken/Ribs/Pork contest at a county fair this weekend and will definitely have less than $500 in it for entry fees, meats, ingredients, gas, and other assorted supplies combined. Doing another Competitor Series event later in the month, same deal.
Also don't feel like you need to take classes and buy a bunch of fancy smokers or trailers to get in on the fun, many successful teams do it with a popup tent and a couple WSMs. Find a local contest, bring what you got and give it a whirl. You'll have a blast and meet some of the greatest folks you've ever known. Smoke on!