This pond kinda shows my point:

http://brainking.com/game/Pond?g=108&trnst=2

Grenv bid 511 but was outbid by 523. There were others who bid 500+ as well, so they show the example of what happens when several people aggressively pursue the bonus.

But there are two things a player can do:

1. Minimize losses
2. Maximize gains

I am pretty sure some of you are well on the path to the right track, but you are using intuition (how else you can explain the "511") rather than deduction (a formula that will let you outperform the field.)

I joined a pond of 50, so now I know there is a target on my back