Call Three Dealerships
This more traditional method may take a bit longer than an instant price, but it is still very effective. Call, text or email the internet sales manager of the dealerships near you. Make sure to include the stock number of the vehicle if you've found it on the dealer's web page. If not, the internet salesperson should easily be able to locate the car you want.
It helps to have a first and second color preference, as well as knowing your "must-have" options. The initial question might go like this:
"Hi, I'm Ron. I was looking for a 2018 Toyota Camry with leather seats and the safety package. I like red the best, but I'd be OK with a blue one, too."
The salesperson would then narrow down the choice for you, and, we hope, confirm that the car is in stock. A good reply on your part would be, "What's your asking price?" This is a soft way of asking them to make the first offer. A number of people make the mistake of saying, "What's your best price?" This approach can come off as abrupt and standoffish, which goes against the rules of negotiating. More on that here.
If you get a price over the phone, ask that your contact at the dealer also email it to you so you have it in writing. Now, do that at least two more times and you'll get a good idea of the real-world prices for this car. From here, you can either take the best offer or, if you like the price from dealer A but dealer B treated you better, ask that dealer to match the price.
In some cases, you'll run into dealerships who will ask that you come down and test-drive the car before talking price. Not every dealership will be willing to make an upfront offer for fear of the customer then shopping the price elsewhere. Thank them for their time and move on.