Are all $100 PAMs JUNK? No.
Are $100 PAMs capable of passing as gens? Probably not, especially when the person inspecting it has seen, or owned, a gen PAM or two.
Honestly, if all you want is a manual wind Panerai rep, and live in an area where most of the populace have never even heard of Panerai, then PWC/T4D/Robert's $99 111 will suffice. But if you plan on wearing it often, it would be a good idea to get the movement serviced.
However, if it is an automatic PAM you're after, plan on investing at least $400-500 into a good one. That includes the cost of sending it out for servicing after you've decided its a keeper. The main problem with PAM, and other brand, reps is the condition and type of the movement in it. Servicing will usually put your Asian rep on par with the ETA counterpart.
This is where the price starts to rise, as an A7750 (the Asian workhorse that is capable of being nearly as good as the ETA7750 in some variations) movement alone costs over $100.
Another notable characteristic of gen PAMs, that practically no 'out of the box' rep has duplicated, is its lume application. Not only is the factory lume a standard Green, but it also quite weak compared to the gen PAM's powerful Aqua coloured Luminova application. So this will add another $120-150 onto the final price for any true PAM rep owner.
And then we get into all the nuances of each model and shortfalls of their reps, but those and their remedies are too many in number to cover here