If you have a client list with repeats and a track record you can try to value that it, but if you're not selling the "name", too, it won't be as valuable to the buyer.
Note: just read PCDoctor's post and he nailed it better than I.
I know this isn't what you are after, but there are business attorneys that specialize in this type of transaction. If you are trying to get value above the equipment and supplies you might want to consult one.
Yes, it gives me hives to type this!!
Southern Brethren BBQ Competition Team
"It's all about getting paid!" - Myron Mixon
"I love being hated in my hometown!" - David Hair
KingFisher Gator Rotisserie cooker, WSM, Stainless 5 burner with IR gas grill, Turkey Fryer, Weber JD Commemorative grill, slightly used Bandera chamber for future use as a cold smoker, Masterbuilt 40" insulated ELECTRIC smoker