$30 if you take it to Jiffy Lube and let them re-torque the drain plug to yield, cracking the oil pan. Real mechanics cost money, whether it’s a BMW or a CamCord. Unless your car specifies synthetic oil, oil change costs are similar across the board if you DIY.
Speaking for myself, I trust myself a lot more than some grease monkey, since I have a lot more to lose if the car’s motor locks up 20 miles outside of Podunk, VT in 0 degree weather.
Oh, and try changing the spark plugs in many wrong-wheel-driven transverse V-6s for fun and giggles.