I suppose you can save some money buying turned legs at home depot and then paint them. My expierence is most people go black when they do that. The toe kick will already be finished in the color of the cabinets I do not see why you would finish them in the factory color on your own. You should be able to order from most semi custom companies the types of items you specificaly mention already finished ready to go.

I did exactly that with Shiloh. I didn't like the island legs they had to offer, so I ordered online separately, saving more than $200/leg. Since we were doing that my contractor said he would do all of the trim for the island and we'd have it all painted together. I ordered a gallon of their spray stain and our cabinet dealer's shop did the painting for us for several hundred dollars total. It was a bit of a pain with timing, but in the end we got exactly what we wanted for a reasonable price.

We haven't done this yet, but it's in our plans. We're also going with white cabinets. We are customizing the hood, valences, refrigerator end panels, molding and pantry, with our primary motivation being to save $. They say that white's an easy color to match, but if you can get the white paint from the cabinet company, that's an added bonus. I don't have any pictures to show yet. Hoping that we can make it all look seamless!

I work a lot with Woodharbor cabinets, and one nice thing is that you can order your legs and other moldings from White River or Enkebol and Woodharbor will finish them to match any of their cabinet finishes including any color paint. It's only about 50.00 to finish a leg or stick of crown and you get a beautiful factory finish that's guaranteed for life. It also keeps you from paying the high markup cabinet companies put on items they have to buy somewhere else, because you are in essence buying it direct from the manufacturer. I'm sure there are other companies that do it, but Woodharbor is the only one I've worked with so far. You can't beat it in my opinion.

I do this for my customers all the time. Turned legs, bun feet, corbels, shelves, whatever. Usually the paint that comes from the factory is laquer-based. It's easier for a DIYer to use water-based. Take a piece of the toe kick (because it's flat) and have that color matched. And, it's best to go to a place where contractors go.
The project I'm working on now calls for us to custom build the hood and spray to match -- in red! In other words, it can certainly be done and for a lot less than what the cabinet manufacturers charge.