Ran your question by a coin-collector buddy (funny, btw, how people get will latch onto one particular area to the point of obsession huh

.
He steered me toward one particular coin dealer.
He told me that there is a very big difference in price between coin dealers. Around 40%. He's drug me around to a couple of coin shows; they'd be viable search targets. Depends if you're in or near a large urban centre as far as that goes. Around here they're about once every two months or so.
Also says that it's not the best time to buy platinum. Price-wise. Price has soared in the last year or so.
anyways, good luck