Here are a couple of inexpensive 67's. Less than $100 each. If that's too pricey then look around a lot at 66's and buy the very best you can. Steel cents were saved by the truckload. There are lots to choose from. Lance.
I just picked this ms66 up for $23.88 shipped.... EBay has a $10 off coupon code flying around. This might be a good option for you
You know what's funny I have a PDS set in 66 and I have a PDS 2nd 67 and I have n 68 and it would be honestly for me to say that between the 68 and the 67 I see very little difference now between 266 and 68 I see a great difference From the hobby center and think tank of MTS.LLC
Unless you're doing the registry thingy (which I do with Bookers and don't get carried away with things) stick with what Kirk mentioned. In my case 66+ is the best one I have, and I've no need to go any higher......especially with those prices.
So would this be worth anything? And what's with the mint mark? There are also nifty die scratches running under the reverse lettering.