I purchased via Orlando Attraction Tickets. I messaged them via Facebook prior to attempting to purchase, to confirm they were allowed to sell to US residents. I had a hiccup or two in the buying process and used their live chat feature (during their office hours in the UK), and they were super friendly and helpful. I received the tickets via email and have them linked in
MDE and ready for our trip. I also looked at purchasing with Attraction Tickets, and had messaged them and confirmed that they could also sell to US residents. Only chose the company I did because it was a little cheaper.