$3 RB/A with 150 players.
Just late register last minute, take add-on for ~average stack, and play the rest of the MTT as a freezeout.
Likely a lot of players have busted, so you probably only have to get through ~100 left. Assuming ITM is 12.5%, ~18 players get paid compared to 6/50 getting ITM.
So, field side is doubled but you only pay $6.60 total vs $22 and have more 12 ITM spots at the cost of having to get through 44 more players.
If $22 is your total BR, this gives you 3 chances to do well. Also 50 * $22 = $1,100. 150 * $3.30 = $495, assume 100 rebuy and add-on, that's $660 + $495 = $1,155. So, the rebuy is giving a bigger prize pool at 1/3 the price (if you late register). Considering that there can be multiple rebuys from players, the prize pool can potentially be even larger.