Would you use a seller's agent in this situation?

[Aimee B.]

We are wrapping up our first flip project. The house is 95% ready to go...just some finish plumbing, a little more on the deck and some finish electric in the pole barn, and we were going to get it listed with an agent next week. Got a call yesterday from someone who wanted to see the house with their agent now before we list. They came today and are very interested. Their agent said we could save 2% commission if we use her (4% instead of 6%), and she'd take care of everything but can't negotiate for us obviously. I told her I needed to think about it. When she asked what we were wanting for the property I said I didn't have an exact number because I hadn't talked with an agent recently, but was expecting this to be a multiple offer situation on the MLS (she agrees) and told her the range of what I found on Zillow (maybe that was a mistake letting her know I had a range in mind). The house is basically a bread and butter house, but it's on 3 acres, wooded with few neighbors, and has a big pole barn, so definitely desirable. This evening the agent sent me a high offer ($180,000; pretty much at the top of the range based on Zillow sold comparable homes/lot size/barn). These buyers have been looking for this type of property for a while now, and want to live in this particular rural town. I do know they are going to want concession for a new roof ($5,000) which we didn't do when we bought because our inspector at the buy said that although older, it was okay. Also, the agent said we don't have the finish the deck (the buyers want to build something different!), and they'll finish the electrical in the barn. The agent said they won't be looking for a lot of concessions apart from the roof, but they noticed some wood rot on one window sill. These are genuine salt-of-the-earth people. I don't get the sense that anyone is trying to screw us over, but with this being our first deal I am worried that I'll get overwhelmed in negotiating if big stuff (i.e., new septic tank or well needed) or tons of little things comes up at inspection. Or maybe we need to expect more money, even though we're already at the top of the market? That sounds so pathetically greedy. Would you recommend we get an agent to represent us? It'll cost us $3,600 in increased commissions.