so which artifacts are actually worth keeping now? just got back into the game and i have a crap load of artifacts

I very much doubt anyone is going to come in here and give you a comprehensive list of itemized values. List what you got with stats and I could easily tell you the grade of each.

you're right...here's what I have

Power Prism Shards:
9/291/7
8/201/6
8/275/6
9/258/8

Pym Growth:
194/1090
160/955

Chthonic idols:
6/6/8
6/7/5

Fearsome Fist of Farallah:
115/1260/56 brut crit
91/1080/64
125/1440/48

Moonstone Shard:
43/68/3
34/73/3
34/77/2

idol of khonshu:
942
wicked wand of watoomb:
189/23

shield motion tracker:
44/11/1403
45/12/1550

Skrull targeting comp:
71/439
84/490

vita-ray:
37/88/11
44/98/14

mark of the odinborn:
39/45.8
40/45.8

ivory idol of Ikonn:
5% and 4%

ringed ruby of raggadoor:
33/5

infinity formula:
126/40

hellfang of zarathos:
52/3/196

Tome of oshtur:
1920/556/58

repulsor field:
168/15

blinding brazier of balthakk:
683/20%

kree hyper-optics:
81/1221/11%

Super-soldier serum:
26/61/6618/726

All of these items can be useful but at this point in the game really only med-high to high end items are tradeable. Every single one of your items is pretty average. Some you should only keep if you personally plan on using yourself. There's just not a lot of trade value in there. The 125/1400 fist is decent and so is the 9/291/7 pps. Just above average I'd say so they might have a bit of value.

Your best bet is to just make a thread on the main item trading forums and be ready for some low ball offers if any offers at all. Most of your offers will come from new players that haven't had a chance to find some of those items so your "wants list" has to be reasonable based on your value.