Can you make your own black garlic?
You can absolutely make your own black garlic. All that is required is to have the garlic in a vaguely air-tight container (preferably individual wrapped or contained) for 30 days at 140°-155°F.  My method, covered at my blog, is to put the garlic in mason jars in my light bulb heated black garlic oven, which can be made for about $30 and can ferment 12 bulbs easily for about $4 of electricity over 40 days. With the cost of garlic, glue, aluminum foil and the mason jars, the oven with one recipe is less expensive than an equivalent order would be online. 

The first 30 days, the jars are kept sealed in the mason jars, to allow the garlic to ferment properly. After 30 days, the lids are removed and the heat in the box dehydrates the garlic, leaving a dried out head with shriveled black cloves inside of it. The flavor is reminiscent of balsamic vinegar and soy sauce, but without the sourness of vinegar or the saltiness of soy sauce. The oven design is easily doable for anyone of any DIY skill level with access to a hardware store and an Academy (where they sell the Huskee cooler I use for $25).