Do I have to pay the 8.8% sales tax or w/e?

I bought my Rover in Portland

Then when you bring it up to WA, you can register it as a used car and no sales tax applies. No way around it if you are buying new or if you dont have a legal residence in OR to register it at. Cops actually watch for out of state cars (especially nice ones) to see if they see them in the same area several times or can notice a pattern in driving (i.e. your commute.)

It's a crapshoot either way. I paid over $400 in taxes on my CQ when I bought it down in CA. I'm just pissed they can collect that, it's already had tax applied to it when new, what BS!

the price on the bill-of-sale -- I think this is what they call it. Just tell him it helps save you on WA state sales tax. He still gets his money. When you take the paperwork to get it registered, they may question you on such a cheap price. Just tell them some story about the car having something wrong with it that lessened its value. At the least, they'll charge you tax on the lowest resale value they have in their books for that vehicle.

People do this all the time. Not any different when family members "gift" a car to amongst themselves.

I think the seller puts the sales price and signs the back of the title. But, most banks have a boiler plate form that the seller can sign and state the sales price on too -- and the bank will notarize it. Having that and the same info on the title really strengthens your "cheaper" price when you take your paperwork in to get your Washington registration. Oh, and it used to be that you'd have to pay to have the WA State Patrol look at the car and certify that it was legally licensable and smog legal.