New to all of this and was wondering if low serial numbers increase the value of Military payment certificates and allied military certificates?
Not really. Radars and 1 or 2 digit numbers will get attention. Since the number of surviving examples is so small there is little chance to have a collection of them. As a consequence, fancy numbers do not get much emphasis among MPC collectors. Fancy number collectors may give a bigger premium but it will still only be a slight one as the demand just is not there.