I ordered my Premier Equine boots direct from the UK. Even with the shipping costs they were cheaper than buying them from a supplier in the states. I'd just like to say that I am in love with these boots. They don't hold water, turn, and really fit my horse's legs. But I understand that they are a bit high in price for them to be for everyone.
Other than that I've had great luck with anything by Woof. They make some great boots! Cheap, durable, they don't twist or get heavy in water. So to anyone new to the sport or looking for something cost effective those would be what I would recommend.