target shooting range

Hi there.
I'm building up a reaction ability target for a shooting range for pistol (9mm).
It's three switches that is targets and a light over each switch in a box, And i only got 12V dc 1.5Amp available.

So i need help with a circuit that can drive 3 relay that randomly turns on, but there can only be one relay that is "on" at time. and stops/freeze after 7 times and then reset by switch to start again. speed/time on how long each relay is on need to be adjustable also.

anyone that can help out? if somebody could build it tell me a price.

You should have a look at a PIC chip. simple logic can calculate a random number and do a timer.When the timer reaches 0 outputs can drive transistors that can drive bulbs and relays. An ADC can be use for connection to a potentiometer and a switch can be used as a reset. I can draw you a schematic and a sheet of materials and code if you would like me too. just give me a PM