There a few used Mean Well switching 7.5VDC 36Amp power supplies on eBay for $15+$9.99 shipping. Item 171225525766 or search for Mean Well S-320-7.5 - seller is electricnurse.
I'm not endorsing these; just passing on the info. I've have been using one for a few months in my main S-100 machine; it's working well for me.
-Neil