Here's what you need to know. The name of the company is Budget. If you get a smoking deal on Priceline or any other website, you're going to have to wait. Sure you could go over to Dollar or National where there is no line but you'll be paying almost 3xs what you would with Budget.
That said, my husband & I booked a car through priceline. For 8 days we got an economy car for under $200. That included taxes, fees and all that jazz. When we got to the rental car facility there was a bit of a line. We waited in line for about 45 minutes. They did have a Budget employee that was monitoring the line and answering any questions people had.
We got to the counter and had our car within 5 minutes. Sure the guy tried to upsell us on a Mustang but after we told him we weren't interested he dropped it. I didn't feel any pressure to add anything else. Originally they were going to give us a Kia Soul. Ugh the hamster car! The guy helped us out though. We ended up with a 2 door Altima with no additional cost.
Drop off with the car was quick. We were upstairs waiting for the shuttle to take us to the airport within 10 minutes of getting to the facility.