Been away from Lake Erie (PA) for a number of years.  Just bought Lake Erie fishing boat but now I need to outfit it.  What is the typical length fishing rod used with downriggers?  I know I need metal line.  What size?  Any good places on the internet to shop for used equipment?
Thanks!

Right here at Fishusa can fix you up with everything.

8ft 6in is a good all around rod for riggers and planer boards. fish usa is a good place also poor Richards bait and tackle good also. lead core  line is a good choice. I think easrier to use then wire line

Maybe I'm misreading your question, but you shouldn't run "metal line" (wire line) behind a rigger.
Same with the lead core suggestion...unless you plan to dredge the lake bottom!
 
Wire line on the rigger itself to the ball - yes.
 
Mono or braid on your rigger rods is the norm. 

Some used trolling gear for sale here. http://forums.fishusa.com/m/tt.aspx?f=30