Good Alternative to Sbooster 12V 0.5A that is less expensive

Get one with a readout screen. I just offered $38 + $12 for one, was accepted and then I found one laying around so I cancelled.

A 12v Li battery. They blow the doors of any power supply regardless of price and you can get them for < $100 on Amazon/eBay 

Swagman Labs
http://www.swagmanlab.com/Linear-Power-Supplies
Quality parts, toroidal transformer, low noise. 12V is $125.

I use one on my digital. They respond to email quickly.

Thank you.  I contacted Swagmanlab.  Looks like the 12V 2A linear supply is the right one.  Sincerely, Don

Hi Don, what component will be using a LPS?

Swagman Labs is probably very similar design to Teradak power supplies.  You can get a small Teradak 12V 2A power supply on ebay for around $130.  I have had good success with using these power supplies.  They aren't the absolute best and the regulator circuit is somewhat inefficient which makes the unit run on the warm side, but it is significantly less than the high end power supplies such as Farad, Teddy Pardo or even Keces.

It's possible they are a similar design, but Swagman will customize a component for you and also offers a premium level LPS which uses Japanese internals. Based in HK.