In general, 17th century Poland is a source of many inexpensive type/date minor coins for world coin collectors. The poltoraks (dreipolkers), solidus (schillings), and even 1 and 3 groschen coins of Sigismund III (reigned 1587-1632), and the tiny copper "boratynki" (schillings) of Jan Casimir (1649-1668)are good examples.
But for Poland OFER (One From Every Reign) or OFEY (One From Every Year) collectors, two reigns are very challenging: Wladyslaw IV (1633-1648) and Michael Korybut (1669-73).
Although Wladyslaw had a longer reign, only thalers, half thalers and ducats were minted during his reign, because of the prodigious minting of minor coins by his predecessor, Sigismund III. As a result, coins from Wladyslaw's reign are all but unattainable for many collectors, with thalers in VF with middling eye appeal upwards of $1,000, and higher grades climbing steeply from there.
Korybut had a much shorter reign (4 years, 4 months), with even fewer types produced than Wladyslaw. The two large denominations which show up most commonly at auction are even rarer than the large denomination Wladyslaw types: the Gdansk (gold) ducat sells at $5,000 and up, and the silver 1/3 thaler from the Bydgoszcz
Royal Mint goes for around $10,000.
Fortunately, the city mints of Gdansk/Danzig (1670), Torun/Thorn (1671) and Elblag/Elbing (1672-3) issued billon schillings/solidus (about 10% silver) covering the same years as these rarer types during Korybut's reign. The ones which bear dates are rated R3 in Kopicki, and remain attainable, though not cheap, in circulated grades. The examples shown below were all graded as VF by the respective auction houses, which is often not terribly attractive for these coins, especially the Elbing schilling which has been called the worst executed modern coin of the Polish kingdom.
I've been fortunate to just complete a set of dated Korybut schillings for my Kingdom of Poland/Lithuania OFEY. Here they are, with Krause and Kopicki catalog attributions. They are also in Numista under Poland-Lithuania Commonwealth, starting here:
https://en.numista.com/catalogue/pieces96419.html