I like seeker, though he seems really week to me. i guess the best way to look at him is as a band of misfits that can copy an card, also adds a woodcutter but has to trash the chosen card. or you could see it as a grand market which draws any card you want, but has to trash it later. neither of that seems worth $6. have you considered making it non-terminal? that would make it much more reliable, since you can always dig for your draw.
with fortress you get a woodcutter-lab-double village (+2 cards, +3 actions, +1buy, +2$)
if you do change it so that you always trash the revealed card, you get a cute way to snipe curses. and you can always use it as a chancellor with +buy.
If you have to tweak it, I'd make it stronger rather than cheaper.
Action - $4 or $5
Discard a card. If you do, and it was not a Victory card, gain a card costing equal to or less than it.
I'm almost certain this is not worth 5$. discarding a good card is a huge penality, so you'll probably want to use it for 5$'s or 6$'s, otherwise it's a really awful workshop. The official cards that can reliably gain cards costing more than 4$ are Horn of Plenty, University and Altar, HoP being the most similar one. It's not hard to get HoP up to 5$ though, which is usually where you want it. With your card, you either have to discard another 5$ or a gold, and both will hurt a lot. now consider that HoP is also non-terminal, can't be drawn dead
and can get provinces in the end game. it seems way stronger than Hooligan, so much that I'd probably try Hooligan at 2$. Think about it, you almost pillage yourself in order to get a good card.