Why would anyone bother claiming to be one of the surviving retainers? There was no fortune to be had.[/color] 
IMO, most of these claimants did not do it for the money, since they were too mentally ill to even be that logical (although some certainly were), but most did it for "prestige" it brought them in their own minds. After all, when someone has delusions of grandeur, they would not imagine themselves to be some random retainer, but rather go all the way and become royalty. Regardless, as per Robert, it sounds like there still were some who claimed to be Demidova, etc... So there are no limits.
BTW, the last Imperial Family Romanovs were not the only ones who were plagued by claimants. Some centuries prior to this, there was the "False Dmitri", Fake Emperor Peter III (I think it was Emelyan Pugachev - if I remember correctly -and a couple of others), as well as a couple of "royal descendants" thrown in for good measure, such as Elizaveta Tarakanova, who claimed to be the secret daughter of Empress Elizabeth Petrovna... I think even the Emperor Paul, or two, came out of the woodwork at some point, as well Alexander I. There were many more, but I can't think of them right now. So none of this is new at all!