What happens after agreeing to a price?

FIRST> get EVERYTHING in writing.
Such as;
WARRANTY including all terms and conditions. Where work has to be performed. A warranty backed only by the dealer does you no good if you are traveling cross country.

The dealer probably will NOT do an inspection before he puts the unit up for sale so this should be done BEFORE you sign not after, even if the dealer BS's you about doing it when you pick the unit up.
BEFORE you sign make sure everything works. I mean everything. If something does not work then it should be written in the contract that the item will be repaired or replaced before you take delivery.

Ask the dealer what terms he can get you on the loan, but of course you are going to a bank or Credit Union first to find out what the going rate is. If dealer is higher than what you can legitimately get and the terms are equal give the dealer a chance to beat the rate if he cannot BEAT the rate you got then go with the place you have

DO NOT TRUST the dealer. Have everything in the contract before you sign.

Make sure you have looked at the blue book price for the unit before making an offer. Start well below that price when dickering. Have a maximum number set in your mind before you give your first offer. If you reach your maximum number and the dealer wants more then you NEED to walk away.
A minimal deposit of $100 - $200 is the max I would give to bind the contract before picking up the unit. Even $1.00 will bind a contract but no dealer will take that small an amount

Once the dealer has your signature he is in the better position and further negotiation is usually not possible, until he has your signature on the contract everything is negotiable.

ALL DEALERS will try to get your money with as little effort on their part as possible.

IF IT IS NOT IN THE CONTRACT IN WRITING THEN IT NEVER HAPPENED. No court will back you if you rely on a dealers verbal promise when there is a written contract.

If the dealer does not want to do business your way before you sign a contract then go somewhere else because he sure as heck isn't going to do business your way after he has your money.

The dealer is not your friend. He is not doing you a favor. The salesman is a machine trying to suck as much money out of you as possible. The more he sucks out the more he makes.

I personally would not buy a used unit from dealer but that is my personal opinion

I would help if you know what it's worth. You can go to WWW.NADA.COM put the make and model in and get somewhat of an ideal of what it's worth. We went to our credit union and arranged a deal before we went shopping. We bought off Craigs List, but you must be very careful doing that. Good luck. :)

Usually, when you buy a used product, you buy it "as is" unless arrangements are negotiated to make repairs. But get it in writing, and be specific.