The caps (dust seal) that protects the oil seal from dirt, are not expensive.
The procedure though is full fork disassemble so it is best to replace the oil too.
Same thing like changing the oil seals.
I wouldn't complain too much about the cost. The tools to do it yourself will cost nearly what the shop charges for labor. Don't forget the main benifit of using a shop is that if they screw it up, you can always take it back. I don't have much faith in shops though and do all my own work.