Utilikilts tends get their non-kilt items from outside vendors, and the socks I've seen them carry seem to all come from Sock Dreams. They're inexpensive but not very cushioning. I mostly end up wearing some wool blend hiking socks I got from Costco and those work well.

As for the kilts themselves, I'm fond of the workman's model. I started with an original, and it's good, but I like the heavier fabric of the workman's. The tradeoff is needing to iron it to keep the pleats vaguely straight. It's not a dress kilt, but having the pleats straight makes it look better, in my opinion. I've read recently that you can put weighted binder clips on the kilt as it's hang drying to achieve the same results.