US Airways has a good policy. I've flown 4 boats down to CR and seen their policy change in the process. Right now, they let you bring your boat and paddle together for $80. Unfortunately for left coasters you have to fly through Charlotte.
I think it's a good idea to call ahead and tell the phone agent to note on your ticket that you have an oversized bag of "surf skis" or surfboards and ask his/her name and badge i.d., if possible go ahead and pay for it. Then when you get there it seems more official and they're expecting it. Most of them don't know how to do a refund so they'd rather just stuff it on the plane.
More than anything I guess it's most important to decide what your willing to go through in advance. If you don't want the hassle then don't bring it. If you don't mind paying the normal fee and going through a little hassle then bring it and make sure your ride to the airport can take it home with them if it doesn't work out. If you are definately going to take it with you then bring it and don't take no for an answer. No matter if you choose option 2 or 3 go EARLY.
I live in San Jose and have a few boats to rent so if you have any questions about CR or are interested in renting you can e-mail me at firstname.lastname@example.org