Don't get too excited. The same reasoning has been used for all series... the high denominations are produced in lower numbers, so logic tells us special numbers should be worth more, but the opposite is true. I've found $50 and $100 radars to be virtually unsalable in all grades. Radar collectors collect the number, not the note, so a $100 face value is tough to swallow when the same sum can purchase several $5 and $10 radars.
The first of anything is bound to generate a lot of interest and some higher prices. I would get rid of a $100 radar ASAP. What you say about Unc grades being difficult is hard to fathom. I just got a bunch of $100s from several different bundles and Uncs were well represented. The high denominations don't circulate as quickly as lower denoms.