I made it to the Japanese market in the city earlier this year and stocked up on pork spleen and kidney. Unfortunately, they don't carry much beef organ. The market closest to me sometimes has beef and pork liver.
But I found an unlikely new source: the farmer's market. They occasionally have lamb kidney but that is now a hot food item. But they have a hard time moving beef kidney so I can pretty much get as much as I want. I've managed to score about 5 lbs. of lamb kidney total plus I can get cuts of lamb from them. I'll be asking them about pork and beef organs this week.
The co-op had a surprise emu order from the the original supplier in Montana. I was able to get 1 of the 5 cases of boneless emu scrap they were offered. Chance loves emu! It's a very dark red meat.
Adventures In Raw Feeding: my woman's blog!