Agree with the sentiments about ammo quality. I know I would look less favourably on, say, a .22 if there were boxes of Remington Thunderbolt in the photo. Rightly or wrongly, we infer certain things from what we see. I remember looking to buy a used car years ago and in looking at some online postings, I zoomed in on the tires - I could see that the seller bought these extremely cheap "Sailun" Chinese tires. Whether it was fair or not, I wondered what else was skimped on in regards to the parts on this car. I passed on the car.
Tying the gun to the ammo as a condition of sale would may cause some more logistical headaches as there are few choices to ship ammo that won't make it cost-prohibitive. Locally, someone may be less inclined to buy the gun if they see that the ammo is priced into the sale. Depending on what the ammo is, I'd just sell it separately (now or later), or if you have something else that can shoot it, save it to use it up on that.