You could try the skeeter pee recipe. Not a beer but pretty good and super cheap. Seems to be the only thing I brew that my friends will regularily guzzle down by the carboy.
Lemon itself can be very hard to ferment, maybe it's the acid content or lack of nutrients. That skeeter pee I'd mentioned calls for starting with a yeast slurry to get it going and all my attempts to start without produced that rotten egg smell. I don't see any reason you couldn't add some lemon to a regular beer recipe after fermentation or perhaps lemon grass for a touch of lemon without causing problems in fermentation.
Best of luck this sounds like an interesting idea.