I wouldn't want anything done to the brass since I do it all myself but I believe I seen a thread on wanting a brass prep service so offer it in both conditions
A couple things I've learned for successful brass sales.
Sort brass by headstamps,
No one wants brass they dislike
Ship via USPS flate rate box,
More bang for your buck
Fill the box with brass,
Again more bang for your buck
Money back guarantee with short time limit,
Handgun brass no problem, but rifle brass can be, treat people well and they will come back
I usually set my price about .20 cents above the local scrap price, the last time I took in brass they were paying $1.60 per pound
, Or you can check completed auctions on Evilbay to see what the market is doing.
By the way, you can order USPS flat rate boxes online for free, print the shipping lable and pay shipping shipping online, and have your carrier pick it up.
Good luck, Ron