What are FA Budgets worth?

For the first time, I'm in a league that uses FAB. I have couple practical questions and then a couple strategic.

1. What's the rough average winning bid for post-draft rookies and then for unrostered early-season surprise performers?
2. What's the rough average for a street FA for a plug-and-play?

Strategic: The league has a huge bench (16 spots) and a huge taxi squad (4 spots), but still only 4 draft rounds. So the only targets on the waiver will be UDFA rookies (in the first days after the draft), veteran schmelvins, and maybe one lucky penny left over for a week 1 surprise. How much FAB is needed to get through those early UDFA days with a bit left over for the lucky penny?

Also strategic: what sort of draft pick could one trade, for example, $100 FAB for?