I doubt you'll find any, will probably have to have pieces plated. And you'll need to find someone who does it correctly. Don't know if the increased resistance to oxidation will offset the cost. But if you do find a source I would be interested. There might be a slight increase in conductivity vs. the existing contacts also, especially if they are not clean/oxidized.
Oh for sure. Unless rhodium plating is added to the design specs, it's very rare that anyone would spend the money doing that unless they were trying to sell add-ons like many "high-end" modders do. ($50 for a plated screw? Nah...)
I've been looking into Rhodium for quite a while as I have a few mods that have rhodium pins/contacts. It does add quite a bit to the conductivity, but most importantly the corrosion resistance keeps the contact clean and smooth. 99% oxy-free copper would be ideal, but due to corrosion, and buildup from batteries arcing (the REO is notorious for this) that conductivity gets worse and worse, resulting in misfires. This happens in very short order, so plan on cleaning those at least every couple days. The mods that have rhodium plated contacts however require very little maintenance, and certainly no resurfacing.
I'm currently researching the best places to get custom plating done, and it looks like the best bet is local jewelry shops, unless someone knows of something better (I would love a good priced online shop with quick turnaround, lol). Because it's an electrochemical plating process, there are some very nasty chemicals involved, and high powered power supplies. Kits are like $1000, otherwise I'd do the plating myself. =) If I get some parts done, I'll be sure to let you guys know, and I will be doing a decent quantity of them (20 or so) to make it worth the trouble. I suppose you guys could get half of them if they are decent.