Yes, if the tickets is from Basel Euroairport (not just Basel SBB), then the bus to the main station should be included. I did this the other way round before leaving to Asia (in TPE now) and it was 16.90 if I remember correctly.

I will also try to catch the last train from Basel to Zurich on Friday night, and will have my car near ZH main station. No more free seats though, they've been snagged by FLYGVA, Frequent_Flyer1 + 2.