Kevin's correct. I was the one that discovered the shoes they used. I looked at photos of the prop display from last year's comic-con and matched the sole details (diamond pattern on the sides, pebble texture underneath) to a pair of skechers I found while shopping at Academy Sports.
Here's a good shot of the shoes. I bought a pair of the brown Skecher Diameter Garzos based on this pic.
However, a few months later this picture surfaced showing showing starlord's back. I cropped it down to just focus on the boots.. You can clear see that the shoe soles are the same, but the shoe continues up the back of the leg. Since i know Skechers doesn't make calf-high boots, the only conclusion I could come to is that they pulled the soles off some skechers and built new boots for Star Lord from the ground up.
These are truly one off pieces that were designed to match the spats. You can see leather details coming up from the heels, and a brown leather tab at the top of the calf. Also, and this is especially trick, the boot has hooks or nubs strategically placed for the spats to hook into and secure themselves directly to the boot. So rather than being laced up or using velcro etc, they are integrated with the boots seamlessly.
I would love to see these boots made custom, but I don't know if anybody here is an experienced cobbler that could put them together. I had a pair of spats made by a leather worker on etsy that you can see in my thread. He did a pretty good job. The color isn't exactly what i want, and the toe piece isn't as accurate as it should be, but they pull off the look very well.