plenty of different places online, even amazon. though, the quality of sex toys on amazon are pretty hit or miss, but if you drop a little more money they’ll be probably alright.
generally, though, i’d recommend sellers that specialize in animal-like toys like elypse art or exotic erotic. they tend to be more realistic (since they’re lifecasts) and guaranteed to be made of body safe material. bad dragon, also, a lot of their stuff leans more fantasy but they have some canine or equine toys that can come in different sizes.
i personally went with an inflatable knot 7-inch dog dildo from elypse art. it was expensiveee ($192) but so worth it! feeling the knot expand and getting knotted by it is so good. i’m smaller as well and i felt like the Magic model was the perfect size.