Like many others here, the main reason for me buying reps is due to cost. Sure, I would love to buy gens but i'm not rich.
I've only been getting into rep watches fairly recently after researching it on the forums and online. Before when I used to think 'fake' watches, those cheap $20 watches with all sorts of 'bling' sold at mall kiosks would come to mind. I didn't know there was an entire market of high quality reps that are so close to their gen counterparts and actually look like an expensive watch when you are wearing them. My first purchase was an cheap IWC from Andrew a while back and after I received it I was surprised how good the watch looked (other than the strap, which I have replaced). I later did more research and found out it has many obvious differences from the gen, but it's a small price to pay to learn a lesson and I'll still wear it no problem. I now do my research on models I'm interested in, find out which ones are best for the money and read user reviews to help me decide. I now own a few reps and have a couple more on the way. I still have a lot to learn, but it's exciting for me.
David