Unfortunately, they really don't have much value as far as I can tell. As a relatively new diver, I wouldn't buy old used gear from someone I don't know really well because I'd be afraid of failure that could range from inconvenience to life threatening.
My wife bought me a BCD as a Christmas present, based upon the ones that I'd used and conversation with my instructor. My regulator was a gift from my brother; he gave it to me and went to his "travel unit". I trust him, he trusts it, and I've used it for approximately 40 dives.
I have two dive computers, one was given to me by my brother, it was his spare, and I've used it for almost every dive I've been on. The second one was purchased from a member here at ScubaBoard; I've tested it in a pool, taking it with me as my primary for my next trip - but I'll have the original with me as backup.
I suspect that experienced divers mostly have their own gear, and it's newer.
I think the real value of your gear, as you've described it, is in your memories.