Up to you what you want to do. I've listed items that have gone for less that I'd like, but I've manned up and sent them, because that was the deal.
Hell, I had a wireless router go for 99p, and then had the buyer threaten to give me negative feedback because they expected me to offer them tech support and I wasn't looking at my emails. The f*cker was boxed with a manual.
But on the other hand, I've dealt with nasty underhanded people, I've dealt with people who could have been honest but you just don't know (like the person who allegedly resent the item three times, and who strung me on long enough for the feedback period to expire).
One thing to remember; if you give negative feedback, they get the chance to either f*ck with you (by reciprocating) or to redeem themself by making good, in which case you can change to a positive.