Ordered some State of Missouri Confederate notes off ebay, a $100 and a $50 for $120. I don't know much about obsoletes but I always see these in lower denominations (usually $1 and $3, sometimes $20) for really high prices at the LCS and flea markets. I have a $1 that's rumored to have been in William Quantrill's pocket when he burned down Lawrence so that's pretty cool. Here's the item: http://www.ebay.com/itm/152469407209?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
With respect, and also with the knowledge that I know nothing about these bills. If someone purchases something and they know absolutely nothing about the item they purchased, 99.99% of the time they probably did not get the better end of the deal. Knowledge is power. If you plan to purchase Numismatic related items, you have to put in the time to study it. I recommend not making any more purchases until you feel you know more than people at the flea market, who almost always overprice their wares. Best of luck.
I did check other listings on ebay and saw the hundred going for $70-$100 and the fifty for $35-$75, but I couldn't find any kind of price guide online so I don't know if that's what they're really worth. The information that I was able to find is that very few of the higher denominations were released into circulation, but I don't know if there were unreleased "remainders" or not so that could effect the scarcity quite a bit.
If you google it as a Defense Bond you will find a few different sites that discuss the bills. I found one that looks just like your 100 on a county historical society site. They didn't discuss value though.
Looks like you did some research. I'm not sure if "going for" means sold for or listed for. Often, those are very different numbers. Good luck!
It is a very decent buy at the level you paid. While not rare, there is not a lot available on Missouri. Many obsolete collectors like to try to have something from each state so it provides a demand basis. IMHO