To have my winter wheels mounted, I paid for half-hour of labor at my BMW dealer = $57. I bought the wheels from them so not sure if they will charge more next time but I don't think they will.

For my previous car, I bought my winter tires through TireRack. While the selection and price was good, I did not like having to deal with that particular tire shop (which wasn't even in my town) to have them mounted and dismounted every year.