One of my player expressed desire for artifact/treasure hunting. I am thinking of a few AD&D adventures to convert, but was reaching out to the community to know whether there are WEG/D20/SAGA or fan made adventures in space opera setting you would recommend?

Obviously Beyond the Rim fit the bill but I am looking for smaller (2-3 sessions) type adventures first before to launch them into something like BtR. Some of the ideas from Lords of Nal Hutta and Enter the Unknown again would fit, and I could run with them, but I am looking for more fleshed out material to help me first.

Well, there's a bunch of old TSR Indy games that adapted the Marvel Comics , WEG also tried their hand at Indy . Those might be worth mining for ideas. Or you could go old school with some Two Fisted Pulp Adventures .