If you want some high quality pbt keycaps, you can look for Imsto pbt keycaps, or BSP pbt keycaps. Both of them are really high quality.
For Imsto pbt keycaps, you can buy it directly from Imsto, or buy it from Feng. For BSP pbt keycaps, you can buy it from Originative.
These two have very good quality, but a little expensive. If you are looking for something cheaper. You can look for vortex pbt keycaps.
I think you still can get them from Techkeys.