There's a lot of guys on here that don't make big bucks, are not charter captains, still compete in the tourneys, & I'm one of them. The only additional expense of derby fishing vs rec fishing is the entry fee. The tourney fees are divied up between usually 3 of us so it's not that bad. We fish alongside the pros in the Scottys and the ProAm's under the Am category. Sometimes yer the bat & sometimes the ball.
Those tourneys were set up with bigger entry fees to accommodate the guys that were asking for bigger payouts. The ProAm even set up an Open Division to accommodate the guys that were asking for it. That entry fee is reasonable too.
As bottom-feeder mentioned, check those out and compete. You'll have a blast, meet some great folks, & won't regret it.
The only other thing you can do is grab the bull by the horns and set up a derby like you would want. There are plenty of guys here that would be glad to offer advice on how to go about it. You can get your other friends to help & even ask for volunteers here on this site.
Good luck on the water this year & let us know if you do set something up.