For something casual and simply to start out look for an Uncle Mike's soft holster model 18. I bought it to fit my N frame S&W but it's worked out that it very nicely holds just about every handgun I have in my collection. The Shadow fits it particularly nicely.
For competition use under the clock you'll quickly want to get something more suitable though. A Bladetech with the DOH attachment removed in favour of a regular good and sturdy belt works well for IDPA. Or if you're at all handy look at making your own OWB leather holster and magazine pouches.
Just as important as the holster for drawing on the clock is the stiffness of the belt. Simply put there is NOTHING you will find straight off the rack at the clothes stores which is stiff enough. You'll again either have to buy or make one. I went with the making option along with my first holster for my IDPA setup. Cost for the first setup was higher than your budget but a lot of it is tools and additional material which can be used for other projects. In the picture below I wasn't quite finished. The belt loops still had to be cut and I didn't show the double layer glued and stitched belt that I also made. The magazine pouches are made from Kydex in this picture but leather pouches could easily be formed and stitched as well. DIRECT cost for the holster, belt and leather mag pouches for an IDPA setup should be around $50 to $60 for leather, stitching cord, dye and dubbin for finishing. Tooling to make these things and others will initially add another $40 on top. And figure on about 10 to 14 hours of your time to make the stuff.
Here's a link to a recent thread where I made a similar holster for my 1911. I put a lot more detail into covering how it's done in the hope of inspiring a few other folks into trying this stuff.
http://www.canadiangunnutz.com/foru...ade-another-holster?highlight=another+holster