At what ever price is on the bill of sale, hint-low
key point there. you'll get the seller to sign a bill of sale, take that to DMV, pay taxes and registration, get your plate. if your state requires inspection, don't forget to have done before you go to DMV (yes, go ahead and ride without a plate... with all your docs).
have your insurance info before you go to DMV. also bring the out-of-state title, if you have it.
you can just type up a bill of sale. include this info:
sellers name/contact info/signature
buyers name/contact info/signature
when you fill in the bill of sale info, remember, this is a legal document.