That sounds reasonable to me. I had a front rear passenger fender accident recently and was quoted $4,000-$5,000 from three different Tesla approved body shops for the fender replacement. When I made the decision for which shop I wanted to go with and brought it in, the final bill was $5,700 which insurance agreed to. Keep in mind that I am in the NYC area so labor rate is probably higher than where you are. The fender and materials is inexpensive as you noted but the labor is the main driver here: dis-assemble, re-assemble, paint the fender and then also paint and blend the parts adjacent to it (front bumper, driver door, hood, etc.) and then clean and polish.
You can shop around with a couple of different shops but if you're going the insurance route and only paying your deductible, then just go with the one you trust most that will do the best job. If you do with the shop, I will consider the time you won't have the car and make arrangements for a rental if you need it, especially if the shop is really busy and there is a queue before they even get to your car. Ask the shops what their anticipated time-frame to repair is. You also need to consider the wait for Tesla to deliver the fender (in my case, it was about a week).