I'd search on ebay for a Kepco JQE style supply in the voltage and amperage you are looking for....probably under 20 volts and around 10-20 amps for your application.
Sometimes you can find them as reasonable as $100.00 or less guaranteed to work. That is quite a bargain considering they were like 1900 bucks new.
Be patient and you WILL find one. The Redstone Arsenal is retiring them at a rapid pace and they are popping up on ebay with regularity these days. If you can wait a month or so, and have the time to search and inquire about these units you will be happy in the long run.
If you need something in a hurry, I am afraid you will be at the mercy of vendors of questionable units like the ones commonly seen in slotcar circles.
Many seem to shore up the value and performance of these cheaper units, but even for the most relaxed duty usage they are really poor components for the job. In the long run you will be far happier with a better engineered product.
I could have succum to the hobby grade junk power source majority, but instead decided to put just a tiny bit of effort and incentive into researching REAL power supplies and where to aquire them and I am far happier than many I know trying to make due with what the hobby industry has provided them with.
It is up to you....all I can do is offer a suggestion on a viable alternative to substandard, profit motivated sales sources of units that cost the vendors 20% or less of what they market their supplies for. Any power source that is available at a wholesale level for prices as low as 20 or 30 dollars is a crap shoot.