Ahhh, more proof that despite the auctions in BTC, the drive of value is still coming from how much fiat one has to unload to buy one.
You are not correct, sir.
You would be surprised to know that many do not buy BTC for fiat in order to purchase Casascius, they simply use the BTC they already hold.
If you want to present "proof", then do your homework, instead of basing a conclusion of one sample.
I can also present "proof", E.g. I have in the past bough a Casascius Goldie (ungraded coin) for ~2.5 BTC, I have done it both when BTC was 500 USD and when BTC was at 285 USD. Using the later sample as "proof", that's 712 USD or 1.07 BTC in today's rates, please show where I can buy a goldie for 1.07 BTC? We can also do the calculation premium wise (which is properly more fair), then would the premium have been 1.5 or 427 USD. In today's rate then would that have been 0.6 BTC (plus the 1 BTC), 1.6 BTC in total.
I agree that there is some correlation with USD exchange rate and Casascius, but it is much less dominant than you imply. The most dominant factor is supply and demand.