Well, let me invite you to look through Bohemia catalogue.
If you are aiming at quite expensive coins, look for "Counts of" sections. Coins there are exquisite, but costs a fortune.
- https://en.numista.com/catalogue/lobkowicz_counts-1.html
- https://en.numista.com/catalogue/rosenbergs-1.html
- https://en.numista.com/catalogue/schlick_counts-1.html
- https://en.numista.com/catalogue/eggenberg_counts-1.html
If you want some Numista rare, but otherwise quite cheap coins, look for the coinage of cities - Jihlava, Brno, Znojmo from Bohemia and others from Silesia.
If you want to create some sort of collection, look for Olmutz bishopric, its coins were produced in larger quatities than king's own in some times.
If you want some more costly collections, look for Silesian duchies. They often produced a lot of denominations with same design, so that makes them nice target. Although, high denominations are often very expensive, especially the gold ones.
Let me know if you fancy anything, I could try to look for it in czech internet shops.