YES! You don't need an agent to buy or sell property - although I'd love to have you call me! (Just kidding). You do need a good real estate attorney to draft the P & S for you and handle any sticky issues that may come up ( you can also buy and sell without an attorney, but I wouldn't recommend it). I can recommend a few excellent real estate attorneys if you need one. ( I wouldn't recommend using an attorney who doesn't handle real estate on a regular basis).
Also, you have to get good information on value before you agree on a price - but if you are getting what you need, and the renters have been preapproved with a lender at that price, you are good to go! Protect yourself by having the renters provide you with a pre-approval letter from a lender, or proof of funds if they are paying cash.
If you would like some comps for your area, please don't hesitate to contact me, I'd be happy to provide tham as a courtesy.