BB has announced that there will be a new draft system, but have not given out the details.
In the past it has worked this way: Each league is given a pool of 48 players. You will told a very limited of information about players that you have scouted. You will get a rating of 1 to 5 on some players. On some of those, you will get a second rating of A+ A A- B+, etc. And on some of those you will know know their best position. Investing $20,000 gives you 4 pieces of information. Typically there will be many players that you will know nothing about.
The players will be anonymized. So you might know that player 7 is a "5". Another team will know that player 11 is a "5", but they might be the same player. Yet other teams will know nothing about players 13, 18, and 27. They will be all the same players.
About all you can do is move the "5" to the top of your draft list and the "1" to the bottom. Order those you know nothing about in the middle based on the numbers you use for the lottery.
You will get 3 players.
The drafted players can end up being pretty good. I have got 2 starters (or they would be except they are both PG) and another who is a solid backup.
$20,000 is probably fine for you. There is some investment based on before you started. And you will probably have some teams in your league who won't bother re-ordering their draft list. If you were in D.IV, I'd suggest cutting it back, but you should be able to afford it in D.III.