$50 is not a bad price. Especially if they are using Synthetic.
My wife's Mercedes goes 10,000 miles minimum between changes using Mobile 1. 166,000 miles and no problems.
Going 5,000 miles would not be a problem. Once you use synthetic, the filter needs changing before the oil.
I will take our GS 350 at least 5,000 miles between oil changes and will use M1.