I "P"ed my Silvia (I got a $150 proportional only digital controller) I was going to buy a Fuji controller from the mob in the US that everyone gets them from, but they wouldnt take a credit card payment from overseas and wanted me to wire the money. Also the shipping/handling they quoted me was jaw droppingly ludicrous. I bought the controller and an SSR from RS who tend to be expensive but it was convenient. Then put it all in a plastic project box I bought at Dick Smith which just sits next to the Silvia. All up cost was probably a little over $200.
If you want to see the controller I got, its part no. 360-5052 at www.rsaustralia.com.au It says its a PI controller, but the I part is essentially useless since its set to about 10 minutes and non-adjustable, any for espresso machine control I think you really only need P and D, I isnt going to get you much in my opinion. This unit is a bunch cheaper than a proper PID but you get what you pay for I guess. P only control doesnt let you tune out the over shoot when the machine is recovering from a shot. But for half the price I dont mind.
Edit: Might be worth looking at something like the West 2300 PIDs, RS part no 292-0221, $246 for one or $228 each for 6+