ebay has cheap regs all the time, but many do not have the needel bvalves, but they 18$ or so from marinedepot.com etc and solenoids are also availabel on line if you want to DIY a reg set up.

I got a reg for 15$, a valve for 12$ and a solenoid for 8$.
Add some brass adaptors, I think it ran about 40$ total.
But no shipping etc included. Add another 20$ right there.

Regards,
Tom Barr