The cheapest I found the GC group N tops (which fit, a 92-94 at least), was for $110/pr at oakos. Shipping was $7 something, and I was very pleased with the service. I can't tell you what they're like, though, because I ended up not using them.
Found a less expensive set at rockauto.com , Dorman p/n 665-349 . $34.79 ea. ... now to decide if it'll make a difference between STi Group N mounts, with stock springs & KYB GR-2's.
I didn't change my strut tops when I put in my AGX/H&R suspension. It's plenty tight with stock 220k top mounts so if anything I might just get new stock ones some day.