Find a good Asian Food Market..........
I normally get my marrow bones from Whole Foods. But some of the things I want cannot be found there. I did a search for ASIAN FOOD MARKET and got lots of sites. \
There I find chicken feet, turkey necks, beef feet, beef knees, and on and on. Lots of these do sound kinda gross but the benefits are many fold. I am still new at this broth regimen and am continually expanding and experimenting. Good thing is that I love the taste.
I normally use a large crock pot. I do mine on a screened in porch since the boss does not care for the smell. When i start a batch I wait for 48 hours to get the first helping. At the end of that day, and each day after that, I add back water to the start level. Pretty much a perpetual brew. After 2-3 weeks it starts to taste burnt so I will then discard it and start over. I figure the constant heat kills any bad thing that would normally develop.
If you are interested in a perpetual broth check out this site:
http://nourishedkitchen.com/perpetual-soup-the-easiest-bone-broth-youll-make/
Or you could simply search for more info.
Hope this is helpful. I know it is one of the best things I have discovered.
Corey