More than a few companies have made 1/300 1/285 aircraft models over the years. Many of their pedigrees have become somewhat blurred, (Navwar/Davco to Heroics Ros), and more than a few companies carry other manufacturers product, further muddying things.
Companies that make/made AC but not a Pzl.
GHQ
CinC/Legions For Hire
Raiden
Falcon (defunct)
Skyraider (defunct)
Beware any search in Magister Militum. They carry 1/300 and have a Pzl, but theirs isn't 1/300. Its 1/600.
Heroics Ros had a line of 1/300 Polish AC, but their website page on that is currently blank.
Scotia/Collectair make a Pzl. This may be the same model carried by MSDgames.
Shapeways has a Pzl. It's a 3D print, so expect it to be very crisp, but possibly fragile.
BattleModels.com from Poland itself has a Pzl, but it doesn't look like much.
Irregular Miniatures makes a Pzl, but it looks kinda "chunky." I found a 1/300 Stuka in a flea market I really liked and drove myself nuts trying to find who made it. It turned out it was Irregular. I found it by accident looking for Car Wars stuff. :)
Hope this helps.
k
is back from Council of Five Nations.