So, if you are playing a 1r/1a rule in the 3.30r and then the 8.00, and play an even mix of them, your average buy-in is $8.65 (9.30+8.00= 17/2 = $8.65), but we will assume sometimes you are reloading in the rebuy or busting before that and opt to not re-buy, so you have might be at an average buy-in of $9.40 (6.30+15.30+8.00+8.00 = 37.6/4 = $9.40), so somewhere between 8.65 and 9.40 x 500 buy-ins would be $4325.00 and $4700. Yes, more conservative, but you won't be reloading, and if you need to step down to 2.50-4.40 range for awhile, you always can, rebuild, and come back up
BR suggestion is $4325-$4700, a very conservative one...