Hi Greg, putting a value on zeenuts is very tough for a number of reasons.
First is they are very thinly collected so unless you get a deal in the first place its real easy to lose money on any quick flip, imo thats why you dont see a lot of them on ebay.
Second I dont know of anyone collecting a graded set other than 1911. look at the PSA/SGC pop reports and its laughable.
1911- 112
1912-27
1913-7
1914-4
1915-7
1916-13
1917-4
1918-3
SGC has graded more but still small when you consider how many cards are in each set-
1911- 879
1912-259
1913-59
1914-96
1915-49
1916-78
1917-56
1918-18
Third the cards are normally in such low condition that no one really even tries to collect high grade, the few people I know working on sets only seem to upgrade there really poor ones to presentable.
Forth from what I have seen most type collectors prefer to find them with coupon and they would be one who would pay a higher price for a higher grade. The cards with coupons bring high prices 3-10 times what ones without do, thats where the action is.
Finally, I saw the cards you purchased and they are very nice, congrats. I would think you paid a bit of a premium (I do on some zeenuts too) and would lose money if you tried to flip but great cards to add to a collection and enjoy them.
