Below you will find stuff from raw PCB's (Printed Circuit Board) to half-finished BI8 boards and LP11 buttons. Only buy the stuff if you know you need it after having been around my development wiki where I keep information for "makers" up-to-date.
Wonder if you can take on the job of creating a "BI8" board yourself? Well, watch this video and you will get a good idea about how complex or not it will appear to you. Basic skills will include soldering and in this case soldering really tiny components. However, with a good soldering iron, a steady hand and some additional tools and tricks its absolutely possible. Generally you can find information about the products and how to create them on the wiki pages.
I2C enabled button interface board for up to 8 illuminated push buttons. Buying options are Raw board, Board w/5 buttons, Board w/8 buttons. The buttons are LP11 buttons. From 148$
Basic PCB with two encoders and pull-down resistors mounted (not shown on picture). Price 91$
Basic PCB with a linear 10K slider mounted. Price: 79$
Various formats of the BI8 board without any components. Fixed price, 17$
Any of the board designs found on the GitHub is for sale as a raw PCB without any components. Fixed price, 17$.