There is a northern tools store now open in Tampa. They carry 60PSI 1.8PH Shurflo Pumps, for about $60.

You'll see people selling 60,100,150PSI pumps for different prices, but they are virtually the same.

There is a pressure switch on the top that determines the PSI of the pump. I learnt this a couple years ago when I traded up for a 100PSI pump and paid over $100 only to find out the switch was the difference.
These days, I have bypassed the switch and am running well over the advertised 100PSI mark.

Anyway, if you're looking for a simple WI kit, this pump is a good starting point. You can always bypass the switch for higher pressure, or swap out the switch for a higher one, while paying less.

A basic kit can be done for :
$60 pump
$15 pressure switch
$15-20 check valve or $30 for a solenoid
$5 nozzle.
Less than $10 in 300PSI nylon tubing at Home Depot
Couple $'s on wires.

I've been running my kit for about 2 years now, no problems. I started with a basic home made kit, spent uneeded $ on a 100 PSI pump, and eventually purchased a progressive controller (PC) in my quest to hold HOM on Stage3.

I've learnt that the PC is nice, but not necessary to see results from WI.