That bike you pictured looks beautiful! Of course, my fixed-gear bike (see link in my sig) has a beautiful Carolina-Blue paint job that was original to the bike!
Two downsides to the powder-coating process are that it's very difficult to do the bike in multiple colors (and you've already planned for this by getting your two colors on the frame and on the rims), and that available colors are limited. Most powder-coating places will mix custom colors for you, or buy special powder for a certain color, but powder is purchased in bulk and you might have to pay for the whole bag of powder if you want a color that the place doesn't usually use.
Usually, people find a machine-shop that does powder-coating of parts for whatever (automotive, industrial) applications, that is willing to run a bike on the side.
If you want frame/fork powdercoated, and then rims powdercoated a diff color, expect to pay over $100 if you have the place strip/sandblast the stuff first for you, maybe $65-90 total if you strip everything yourself.
You could paint over a powdercoat, but I don't know how well this holds.
If you know exactly what you want and are willing to pay for it, I'd recommend going to Spectrum Powder Works
. They do multi-color powdercoat jobs, beautifully finished, and will get the bike exactly as you want it. Probably close to $200. But they're worth checking out, especially if the bike and componentry are in good shape.