Alright, they're not 8" speakers but will still easily fit as 6x9s.
6x9 Subwoofer - 2ohm Xmax - 8mm
Qts - .80
RSM - 50w
Price - $4.89/each
You could probably fit up to 4 or 5 of them across the rear deck (at a total cost of only $25). They won't need a baffle either due to the included spacer. The 2ohm impedence gives you some interesting wiring options too.
