crx-free
+motor (B18B, h22, crvtec, K-series, etc)
+goodies (S/C, N/A build, turbo, piping, IC, management)
____________
=$3,000-$10,000 depending on which route you chose


Trans Am- $13,000
+goodies
____________
=$15-16,000

If your goal is simply to have a 12 second car, the CRX is far more practical and affordable... namely, because you already own it, its free and there are a thousand ways (of varying degrees of cost) to get it into the 12s.