The least expensive, linear power supply that will work with an SB3 is the Jerome Industries # RYD313F-001
It has an IEC power inlet, so you can experiment with different AC cables.
You will have to cut off the DIN connector that is on the end of the DC cable. You will have to install (solder) the correct DC connector onto it.
The best thing is it is only $10.00.
It is available from Herbach & Rademan
hereI believe they have a $20.00 or similar minimum order. Take a look around their site. You should be able to find something else you can't live without.
I do offer mods for this PS and I do sell other more expensive PS for SB3.
Happy Holidays