Can a used car dealership switch the price I saw online vs going in and getting a different price?

It doesn’t matter whether it is legal or not. What matters is that this car dealer is trying to rip you off, so you tell them where they can stick their car and buy your car elsewhere. You definitely don’t want to deal with a car dealer that tries to rip you off, you will have more problems with him.

PS. There is no reason why financing the car should make any difference to the dealer, quite the opposite. If you finance the car, the dealer still gets cash (or a cheque or whatever). If you finance through the dealer, they usually get some money from the finance company, so buying cash is often worse for them.

Gnasher is 100% on point.

One option, that is far better than accepting the dealers financing is to obtain your own. Go to your bank or credit union and ask for an auto loan. Often times their rate will be much better.

My recommendation would be to play them at their own game. I will pay 12,995 for the car and not a penny more because you guys are being frauds. After some battling I would be okay if we landed at 14,995, but I would at least make a pretense.

If you are going to finance a car, please shop around for the best local bank/credit union. they have far better deals than what you can obtain from the dealership most of the time.

A far better option would be to pay cash for a car as once a person gets on the cycle of car payments it is very difficult to get off. Do you really want to commit to this kind of dishonesty for a significant portion of your life? Buying your cars with cash gives one a lot more options and negotiation power. It is tough to get started, but you will save a ton of money.

Financing can include all taxes and fees, which according to https://www.carmax.com/car-financing/car-payment-calculator is estimated at around ~$2,225 for a car sold in Arizona. Of course used car dealerships are notorious for unethical sales techniques, but it's not clear that there is anything unusual going on beyond standard taxes and fees being added in.

Note: These taxes and fees can be significantly different from state to state, with Arizona being on the higher side. Buying in Phoenix will really boost that up since the city has a 2.5% sales tax in addition to the county and state tax.

If your buying a car, the dealership doesn't honor your agreement, or adds extra charges, then its ok to walk away, in fact its the best thing to do. They think that you will go spread the news that they might have "ripped you off" and will try to get you back. The trick works every time and they know it.