generic POH
For some older aircraft generic POH's are all there is.
Cessna used generic POHs on the 150 to about 1978, when it became the 152, and the POHs on some of them ('82 and up?) are serialized to the individual airplane. The generics are on eBay for $10 all day long, the serialized manuals come only from Cessna and can cost well over $150. (add more, lots more if you are not in the USA and/or you need it in a hurry)
My 150 is a '67, and there is only a generic POH for '67 models. I also have a POH for a '67 Mooney, which is a rather more complex and somewhat faster airplane than a 150 (but to be fair, most aircraft are faster than a 150), and it is so simple as to be laughable - or scary. It doesn't tell you much more than the pointy end is the front and to please be careful - after that you're on your own.
I've also seen generic POHs for Piper Traumahawks (1978) and Cadet/Warriors (1989/90). They caution that these are ONLY generic POHs and are not the OFFICIAL POH for flight use (those are serialized to the individual aircraft).
I think the original question should have been phrased as "where can I find a POH suitable for a BugSmasher 200B, serial number XXXX".
Best Regards,
Echo Mike