Is insurance required on jet skii's in washington state? How much does it usually cost a month? Is there insurance companys that will allow you to insurance only a couple of months of the year (in summer)? How much do tabs cost in washington state and are they required for both jet skii and trailer? Does it cost to license a jet ski and trailer? If yes, how much? I've tried to find this info on the search engine. No such luck. Thanks

You'll have to register the trailer and ski in Washington, here's a link on what the cost is most likely going to be:
http://www.boat-ed.com/wa/handbook/index.htm (scroll down to table of contents and click on link, you'll find a section on registration fees and reqs. )

Or here's the direct link:
http://www.boat-ed.com/wa/handbook/toc.htm
The fees:
http://www.boat-ed.com/wa/handbook/register.htm#fees

I insure through progressive, they're the cheapest I've found, but they only sale year long policies. I just cancell it whenever I'm done riding for the year and they refund the unused months. Might seem like a PITA, but it's not too bad, a couple of minutes on the phone is all it takes to renew or cancel my policy, and I never had a problem with them.