Yes, you can use just a regular style interconnect.
If it's going to be a longer cable you might want to get one that's shielded.
I personally use an M-80 Sub Cable from Bolder Cables. They have a circle here at Audio Circle.
http://www.audiocircle.com/index.php?board=11He could build you a rather nice cable to meet whatever your needs are. And it'll fall into your price range as well unless you go for something that's waaay overkill for a sub cable.
I'd just make sure you use something that has good plugs on it (preferrably Eichmann Bullet Plugs or WBT NextGen's).
Copper or silver shouldn't matter much in a sub cable.
FWIW I used to have a fairly nice Monster Sub Cable. The cable itself was fine, but the connector's were only so-so. I had Bolder Cables put Eichmann Bullet Plugs on the sub cable I had built & it was a definite improvement. If I was doing it now I might go for NextGen's instead of the Bullet Plugs (Bullets weren't quite available back then).