Sigh, I MAY regret this...
I LOVE black garlic but there are two issues.
1) It is expensive.
2) A unit to make it yourself is a minimum of $100.00.
Fortunately there is another way if you have a rice cooker. I have found several links that state that you can make your own black garlic using a rice cooker set at the "keep warm" setting. Most rice cookers will not have a button for warm but will default to this setting when plugged in. To test just plug in your rice cooker and see if a keep warm light comes on. If it does all is good.
So we now have a usable rice cooker set to keep warm. Just throw in bulbs of fresh garlic and let the rice cooker go for about three weeks and you should have proper black garlic. You cannot do this with a dehydrator as it removes the humidity that is needed for the process. I intend to try this.
So why may I regret? This method is reported to put out a LOT of odor. One report said that it is like living inside of a clove of garlic.
As a side note the stuff is difficult to deal with as it is very gummy and will stain your fingers black if handled. I have found the solution. Just cut off one end of a clove and squeeze out the black garlic like the clove is a tube of toothpaste.
As another side note black garlic is awesome when used with peas and pearl onions.
It also adds a GREAT flavor to chicken or pork. To be honest I haven't tried with beef.