There is probably no transmission in a US road car that can be replaced for $500 in labor at an auto shop. Your buddy or some rando may do it, but no shop will for that price. Typical shop rate is $120-$220/hour. Most shops are going to charge a minimum of 4 hours, but probably closer to 8 hours. Have you ever been under a car? The amount of "automation" required to replace a transmission is still in the arena of science fiction.
I have personally replaced a Volkswagen transmission in under an hour. I did it alone, in a driveway, with a regular floor jack, a skateboard, and a set of harbor freight wrenches.