In this life you either have to spend money or spend time to get what you want. You'll have to decide for yourself which you'd rather spend to get your birds from your yard to your table.
Having little available $$$, I had no other choice but to process my birds myself. Although it will never be my favorite chore, I do get a lot of satisfaction knowing I've mastered this essential skill, and a connection with the many generations before me who have done this exact thing to provide food for their tables.
But I've never had 85 birds to process at once, and assuming they're Cornish Xs, they'll need to be done within a small window of time.
I haven't spent much $$$ on processing equipment either. Just for zip-ties, duct tape, plastic gloves & garbage can liners. I've collected some good knives & big stock pots from FreeCycle & the thrift stores. My favorite piece of equipment is a reclaimed porch swing frame, from which I can hang the birds to bleed & to pluck.
If I had $400 to spend for processing, I would buy:
*A turkey fryer to use for scalding
*Materials to make an electric-drill plucker
*A good filet knife
*A misting fan to blow on me while I work
*Refreshments for my friends who would come share the chore & the meat
I like the idea of doing a few yourself several days before having the processing party. Then everyone can taste the purpose of doing all this work while they're doing it.