Having done a little reading...
The Wandering Jew has a number of forms. While the myth we commonly site today is most directly from Christian myth, the roots are probably much older. If it were purely Christian, the curse would logically be damnation in Hell, not everlasting life. The everlasting life thing seems a holdover from another myth.
The "curse" of immortality is seen elsewhere - in the Koran, Moses curses Sameri the Sameritan to wander the world for helping to create the golden calf. Given that Judaism, Christianity, and Islam are all known for borrowing from older myths, as well as later manglings, it's prety easy to see how there's multiple versions of the story.
As for items of power - I doubt we'll see many. Excalibur and the Holy Grail are too cliche. The writers seem to like to borrow from more esoteric, less popular myths. The sword of Charlemagne is also probably out, because (IIRC) they already mentioned that old Charley carried the Spear of Longinus. No need for a special sword, then.
So far, much of their mythology seems to be Christian - Joan of Arc, the Spear of Longinus, the Wandering Jew. I don't think we'll start seeing items from other ethos - no Mjollnir or Golden Fleece. And I dunno how many other powerful items Christian Myth has in it. The Staff of Moses? I really doubt they'll touch the One True Cross...
Also, using more than one item of power a season (when there's only 12 episodes in each) would be over doing it. They seem to know better than to make it the "power item of the week". Though I think the Golden Apple (the one that started the Trojan War), could be an interesting gambit
As for stuff being "readily available to the buyng public", I have to point out scale. While Gabrial sells minor items, really big things (liek the Spear) are not readily available. Gabriel mentioned that he wouldn't touch it. The Spear had to be stolen - and was paid for by Irons, one of the richest men on the planet. I don't think multi-billionaires really count as "the buying public". The subset of such people who actually believe mythology to the point of spending resources to get such things even less so.
Edit: Hmm. Actually, there is one Judeo-Christian item that might be nice to see - Joseph's Coat of Many Colors. It's got some nice subtleties to it...