How to Price Held Items (ie. storm artifact.)

I wanted to by a storm artifact just a few mins. ago for my ele. But the guy kept asking me for a offer and wouldnt give me a price range. Since i didn't know how to price the item he said to come back when i did. I only price weapons so cud someone help me out with this?

Items:

Storm Artifact
Armor +5 (while enchanted)

Storm Artifact
Quick Recovery form Poison

not worth much if u ask me, i'd give 500g for each if I really wanted them lol

but maybe i'm missing something

Hmm... Idk, it seemed as if he was hinting that they wer worth quite a bit, even though i thought not. So who knows but thx.