I own the M8 and also an Epson (which I haven't used much since I got the M8) and also a D3/D300 and a G1. The smaller cameras are part of my continuing search to find a really good-quality camera that I like, and that I can travel with.
The M8 makes terrific images, but the operation is completely different than a DSLR and I don't know why anybody who doesn't have an specific attachment to rangefinder cameras would want one, except for peculiar aesthetic reasons -- the "look" that James Russell speaks of. It really is a bit different. The camera also forces you to shoot differently, which also changes the look of your photos...and the lenses are a lot different than Nikon/Canons...no auto-focus, which teaches you to be very careful, and slows you down, which again changes the way your photos look, or allows you to speed up, with zone focusing, which again changes the look...A relatively complete Leica outfit may cost more than $20,000, and that's without a backup body. (A new body, a WATE, a 24-35-50 (maybe two 50s) 75-90 and perhaps 135.)
However, if the OP is a professional or an artist, looking for a smaller pro-level camera that's easy to carry, I'd suggest looking at the Pentax K7 which will be released in a couple of weeks. Very small -- not much larger package than the Leica, and lighter, I think -- with a series of very small good prime lenses to go with it, and a couple of decent (not great) zooms. A fairly complete outfit could be had for $2,500-$3,000 or so, or about 1/8 the cost of a Leica outfit. The photos will much resemble the Canon/Nikon/Sony stuff.
Or, if the OP is thinking about a walk-around shooter and wants to explore the M8, a good used body can be had for ~$3,000, and a couple thousand more for a fast 35, and if the experience isn't right, most of that could be recovered in a re-sale.