I looked it up and found this.
UND clean underwear - insulated - full service - EA - $4.20
UND- clean underwear - insulated - drop off - EA - $3.49
If you do it per lb as Mark suggested it's:
AV Laundry wash - wash/dry/fold - per pound - full service LB - $4.95
After you clean them and put them in a box, you can charge for providing the box, they start @:
BX