I bought 2 different MRAD113's from eBAY and wanted to test them to ensure they were working.  One was a new old stock unit, the other looks almost brand new as well.  Both were from back in 2011 or a few years older timeframe.  One had a cal sticker on it, but it's been a while since it was verified.  Considering what I paid for them vs the Accurad (~$230 each  I think, compared to the Accurad which was ~$1000) they are both within spec when testing with a CS-137 source that I just bought.  The Accurad is definitely faster to respond is damn awesome, but the MRADs just work - which is awesome!

Getting some check sources has been on my wish list for a while...

https://www.pasco.com/products/lab-apparatus/atomic-and-nuclear/radioactive-source-cs-137-5-microcurie

$110 here, which is where I ordered mine

Interesting, thanks...

I also took a look at the Spectrum Techniques site where they offer a wide variety of other check sources - but unfortunately it's all "request a quote" rather than directly showing prices for their products.

https://www.spectrumtechniques.com/exempt-quantity-radioactive-sources/

I actually asked for a quote from them and they were more expensive than buying from Pasco.  Pasco was $130 shipped, Spectrum was $160 shipped.  As you can see, it came from Spectrum, so its the same product for less!!