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? 
i know nothing of these specific preamps, and would certainly solicit more opinions, but i've taken a flyer on a number of these cheap chinese clones (dacs, passive pre, headphone amp) and have been surprised at how close they get to their exponentially pricier western targets. again, i'd do my research, but if you can get return privileges at these prices it'd be interesting to try.
@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.
Don't buy and support Ch*neese pirates!
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.