There's a lot out on the auction site if you search for "1:150 horses". I had to fill up an entire circus stock car with lightweight horses (and not go broke) and I got one of those 100 unpainted horses for like $12.
If you're looking for perfect foreground models you can go Preiser or Woodland Scenics, but if you need a herd, this is a solution. I've got some Noch ones for my logging skidder horses with harnesses already on them, but in this situation, when they are semi-concealed, these worked great
The same outfit does 100 of a lot of those, unpainted and painted, they are rather nice for large quantities at a reasonable price.