For UK builders this list may help with sourcing other bits. There are of course other suppliers.
You'll need a few other things to build the eTap2HW.
Below is a list a few of the parts you need which are available from Maplin and also from other suppliers such as CPC, Farnell, RS etc. Of course you'll need an enclosure of some sort to put it in too!
Details of Maplin parts, part nos etc
Pots: Level: Pot Log 1M Order Code: FW28F OR Min Pot Log 1M Order Code: JM80B
Controls: Pot Lin 10k Order Code: FW02C OR Min Pot Lin 10k Order Code: JM71N
Knobs: Up to you to suit the pots
Sockets: 1/4” Mono Chassis Socket HF91Y OR 1/4” Mono Jack Socketwith Solder Tags Order Code: HF90X OR Mono Socket with Chrome Bezel Order Code: BW798K
BCD Switch Thumbwheel BCD Order Code: JK36P
RS Components BCD Rotary Switch: http://uk.rs-online.com/web/p/products/655-3235/