Update:
I ordered a pair of the Tang Band subs from
www.nuera-acoustic.ca for $80 shipped. They'll be going in a ported box in the hatch of my RX7.
As they're 4ohm SVC subs, I'll only be giving them a "rated" 75w each. But, it's probably more like 100-125w each of available power which seems to be a good match as they're rated to handle 125w.
I'll post my impressions after I've designed/built a box and have them installed.
Thanks to everyone for their comments and suggestions.