You can always think outside the box a bit and shop around at some reenactment suppliers, such as James Townsend & Sons.

They have 18th century style buckle shoes for $90.

You have to attach your own buckle (which they also sell, a few different styles from $20 to $50). And these are made in 18th century fashion, which means they are straight lasted (no difference between right and left).

So I doubt they would be quite as comfy as a modern shoe, but they certainly would have an authentic look and the price is much lower than what you'd pay for a buckle brogue at most Highland dress suppliers.