Is Fractional Currency Currently Undervalued?

I think it's way under valued. About a month or so ago I sold my fractional currency collection, had a very complete type set, all of the various issues and all the denominations of all the issues, most were in XF, some Unc, only a few were in lower VF grade.

I was in the process of buying a 1928 $ 500. FRN and a 1922 $ 100. Gold Cert. to complete my $ 500. FRN collection and my Large Gold Cert collection. Thought for sure they would sell for enough to pay for them, not so, it still cost me a few hundred more.

I'm not complaining but they just seemed to book out for a lot more than they sold for, just goes to show that unless your young and going to hold on to stuff like that for a long, long, time you shouldn't be buying currency as an investment, buy it because you enjoy building a collection, not because you think it's a good investment, I'm sure I wont live long enough to see a return on the two notes I just bought but that's ok, I bought them because they completed my 500. FRN and my Gold Cert. collection.
And I'm happy with that.
Bill Collector

Personally, I do believe these little notes are very much undervalued in todays market.
Fractionals are still very affordable in mid grades across the board and anyone can assemble a nice collection in a short amount of time if you do the leg work.
The values will continue to rise IMO, esp the mid and higher grades,
they are not as common as you might think and the tougher issues are increasing in popularity.
I have been collecting fractionals for over 20 years now, and though I am happy to see the prices increase over this time, it is still much less than I imagined, esp in comparison to large type notes, which have skyrocketed in the same amount of time.
Perhaps in another 20 years, these little treasures will demand prices that respect their rarity, but until then I am just happy being able to find affordable notes to collect.