I have read that it is a bad idea to get used snowboard boots because they are stretched and/or formed to someone else's foot. I have seen a few ebay ads that were slightly tempting with boots that had been used only 2-3 times. Is that significant enough to make a difference. Or could that be considered light enough use that it might be worth the buy? Note that these are used version of a boot that I have already tried on at the store and fit well. So I know that a new version of the boot fits well.
I've actually been in that same situation before and so far I haven't been able to pull the trigger on really lightly used boots yet. It's just so tempting if the price is really really good.
I would probably request more pictures to try to visually see if there is any damage, and ask more about how they were used. The rest is up to if you are willing to go for it!
Unfortunately, they pretty much fit like crap and pinched my feet. They had been pretty heavily used. From my experience, I would say don't buy used unless you can try them on. If you can get a significant discount, I would buy boots that have been used by a beginner who got fed up and quite after one day. My wife got a pair of used Burtons on eBay for $1.25 that the girl just wanted to get rid of.