If you only buy CSWP coupon for exam it will cost more, but if you buy Solidworks student version you will get CSWA & CSWP both coupan code 50$ (50% discount right now).
Solidworks student version
Pros: licensed solidworks with both voucher ( if buy separately cost more)
Cons: the voucher doesn't comes with segments, you have to attend 3 hour long exam at once.