There are billions of heads of cattle out there, raised specifically for meat, so where is all this horse-meat coming from? And how can it be cheaper (presumably the reason it is being used) than such a huge industry as cattle?
If one wants cheap, low-grade cow meat - its out there too. Spent dairy cattle, Brazil, etc....
The world demand for horse meat is probably pretty low as compared to beef, so I would suspect that it is very, very cheap......