Bill - I have been through the same thoughts the last year or so, I've done a few of what I call the big tourneys on our lake - 50-60 boats, $50 entry fee (I know i'm cheap! But haven't placed once so $25 from me and $25 from my non-boater is donations), and have finished in the top 1/2 but never in the $$. We ended up a few years ago starting a local pot tourney on the side of $25/boat ($20 to total weight and $5 to big fish) and paid out 3 minimum and more if we had more boats. By the end of the 3rd season we have 30+ boats fishing, and a few of the real "good" guys from the larger tourney's starting fishing and winning. So they decided to up the entry fee to $50, to give larger payouts and get sponsors and givaways... A number of us just decided that wasen't for us, and 1 guy started a Sunday afternoon tourney for $20/entry, you could fish 1 person in a boat, 2 people in a boat or 5 people and decide when you enter if you want each person to fish by themselves ($25 each) or as a team ($25 for the boat). We also set up "poor man" tourneys, Eli and I ran one in the fall, $25 per boat no more then 10 boats, to keep it friendly, small and competitive.
On the Pros in Amature tourney's, I'm with a few others, when you join a trail read their rules (if they are sanctioned like FOM or a BASS club), and make a decision. On our lake there are clubs, open Pot Tourneys, trails where you must fish X number to make it to the 2nd half of the season, and so on... Personaly there are a few tourney's I won't fish (not that I fish a lot) where the few long time locals always finish in the top or win. I know a lot of guys who donate $1000's of dollars a year to fish against those boys every week of the season for the "chance" to beat them, and others like me who don't see the value at my level/experience, so I choose not to.
The key is as Dan said, fish against the clock, do it if you enjoy it!
Trep