Spatterdash makes good spats, I've heard good reviews of them from others, though their style is made to go with trousers. I'd love a pair to go with a 3-piece suit.

Another option is here: http://www.etsy.com/shop.php?user_id=5241258 A look through her sold items shows that she can do just about any custom job you like, and reasonably priced, I'd say.

Speaking of civilian spats, here's a pair I just finished. I made the skirt for my wife and had some fabric left over, so I made matching spats for her. Drafted the pattern myself (I do need to adjust the pattern a bit to round the toe a bit more) and all hand-sewn, including hand-worked corded keyhole buttonholes. I'm going to make her knee-high ones for her when we get a sewing machine, and I'll be making spats for myself as well.

She's wearing them over heels, but there's no difference in pattern, they can be worn over any kind of shoe.