I think the problem with trying to keep the Z in the low $30Ks is that it's not realistic; we're living in an era of $40K Mustangs/Camaros. Times are changing, and even a "cheap" car like the FR-S is still $25K before options. Give it wheels you'd want to be seen with, metallic paint, a radio... and now all of a sudden the 200 hp wonder-car isn't such a bargain compared to your wife's v6 Mustang.
My vote would be increase hp output in the v6 platform, drop a few pounds, and continue to compete with the American pony cars at a similar (or even slightly higher) price point. It'll still sell just fine.