Hey, Steve! Glad you could join us!
I don't know if you've gotten sample decks from USPCC showing what they are capable of with regard to metallic inks, but the best examples of metallic inks that I've seen them print are on the Theory11 White Artisan decks. They also have a lighter metallic (to the point of being more silver than gold) on the Theory11 Medallions deck. Both of these have a little bit of a shine to them, but nowhere near like if they were using a foil stamping process. (If you're not familiar with Theory11, you can find their decks at theory11.com.) The "original" Artisan decks have a silver metallic ink that works well.
Elite's "Gold" deck, which just came out from their KickStarter project (you can probably pick it up on a number of third party sites; if not now, soon), uses a metallic gold ink with black for the backs of the cards. The effect is, like Don says above, a little dark.
The Expert Playing Card company has just released their first commercial experiment with foil stamping on a deck called Exquisite Bold (available from artofplay.com). I seem to recall reading that they have a second, more extensive experiment coming out soon with foil stamping on the cards, but I don't recall which project that is. I don't think it's out yet. (Someone else on this board will recall, and be happy to jump in.
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If you scroll to the top of the Playing Card Plethora page, you'll see that the Expert Playing Card Company has an official thread there, where you can find links to talk to their representatives directly. (Note: I have no stake in EPCC; I do, however, like shiny cards, and want to encourage both EPCC and USPCC to do more in that direction.)
USPCC has the advantage of being pretty much the best card in the world out-of-the-box for cardists, magicians, and players alike, but EPCC is improving all the time, both in quality and in reputation. Would USPCC be able to mix some "metallic" yellow for your cards (in place of what they consider gold)? It might be worth asking.
Best of success to you!