I installed an island in my kitchen in wyoming that was just a grow. I cut a hole in the floor so I could build a plastic lined bottom in my crawlspace and the plants had 6 feet of room to the bottom of the countertop from the floor of my crawlspace. The whole thing cost me $650 bucks, but nothing beats eating breakfast with a girl on the top of your grow and her never knowing
I also made my own countertop for it since I had formica already, or that would've probably been another 100 - 150.
I've grown under my sink and in my dish cupboard before too.
Couple tips for ninja growing-
light leaks are little tattle tales waiting to happen, smell and fan noise is another. Seal everything with weather stripping, and put your fan under your house with a duct leading from your grow to the fan. Leave the filter right in with the plants. Sound proof everything that vibrates with old towels or something. That way the noise at least isn't by your op. Use low wattage compact flouro's with coverings on them so the plants can just hug them without getting burned, or use 4 foot flouro's that won't burn them if they touch them.
edit-
when I sold my house it cost me 40 bucks for a piece of plywood to cover the hole under the island, then I just reinstalled it over the board and put the original drawers from storage into it and chucked the faux drawers. Always plan ahead