i have the JL XR 3 ways and they sound great. The only boston 3 ways will be the older Pro models, you'll have to look on ebay and will prob only find used ones. don't think they have any 3 way models currently, maby some midbass add ons. I had the alpines you mention before, didn't like them at all. JL XR653's go for $300 plus shipping on ebay.
do note that 3 ways take a lot in installation to set up properly. if not willing to spend the time or money on the installation, i'd suggect sticking with a 2 way set. there was a thread on here that had some pretty good detalils on 3 ways vs. 2 ways. search for it if you can.