I cannot say the cheap version is fake due to the fact that it uses Shure voice coil and short cut electronics. Expensive version of Shure uses gold plated circuitry plus fancy electronics. I'd say the cheap version is made affordable for everyone. I have both cheap and expensive Shure mic and both works well.
PG series are the basic model of Shure meaning the price is just half of the SM58, obviously theres a big difference in audio and parts between the two.
Boss suggest lng. Mas maganda parehas ang model shure sm58 pra malaman ang original o fake bka magkaiba ang diagram o board sa sm58 at ska PG series. Salamat