Naim "based" preamps - yay or nay?


I'm a big fan of Naim products, have listened to them a lot as my parents have some of their integrated amps. But I don't have that kind of budget for them. I've noticed, however, on ebay there's a lot of preamps "based" Naim boards (E.g.  Hifi 152 base on NAIM NAC152XSC5 base on Naim 152; etc; etc). While I'm assuming the quality wouldn't be as good as an actual Naim preamp, can anyone speak to the quality of these kinds of Naim based preamps in general? 
gravyrobbers91
@loomisjohnson previously I was thinking these were sort of "homebrew" preamps based on Naim boards, but you're right these are clones, which has me actually more interested. I remember back at music school some of my engineering friends would get clones of classic vintage production equipment, and for the most part worked great, so I might start researching some of these clone products more, as I actually find it kind of interesting.
gravyrobber, if you do get one of those pres let us know how it sounds...curious
@loomisjohnson looks like I'm picking up a Rotel RC-995 from a guy on Reddit today, so probably going to pass on a Naim clone lol.