Used firearms can be a very good way to get a really good gun and save some good dollars and thus a good overall value.
Buying hands on is arguably better than buying online, but only if you know what to look for, how to properly assess both issues and therefore value. It would pay to have someone knowledgeable tag along and give the prospective gun a good look over.
Buying online can be good if you know who the seller is and know that person's track record of both online forum posts and sales. At the very least get a day or so "look over" return, where the lock, barrel, stock, and furniture can be hands-on assessed.