The Klipsch s4i is decent, I've got a pair myself although honestly I prefer my (admittedly uglier and clunkier) Etymotics as far as earbuds go. That said, I wouldn't dream of exercising with either.
You definitely either want some buds that wrap around the back of your ears, or some clip style bandless headphones (like these: http://www.amazon.com/Sony-MDR-Q68LW-Clip-Headphone-Retractable/dp/B000PCF7A6/ref=pd_sim_e_2
). You also are going to want to make sure they are at least semi-open, and have solid construction.
Also, I know you want good audio quality, but I really suggest you don't get too picky about that for exercise phones. You're using you S3, which has good audio for a phone, but is still just a phone. You are probably going to be listening to MP3 or some other lossy compression format. You are going to have a TON of micro harmonics from movement of both the cables, and the earbuds/headphones in/on your ears themselves. You are going to have the sound of your own heavier breathing, and if they isolate well enough even your own heartbeat. And lastly, you don't really WANT to block out all external noises for safety reasons (assuming you don't exclusively exercise on a treadmill in your own house or something) so you are going to have a lot of external noises as well.
After all that, it is going to be hard to tell much difference between a good $20 unit and a $50 unit. What you WILL notice however is a well made design that doesn't constantly slip out of your ear, cut you off from the outside world, or transfer more movement noises than actual music audio.
You will also notice a smaller pit in your stomach (and wallet) when they get all grimey and/or broken
EDIT: You may also consider a bluetooth option for exercise. You lose some audio quality for certain, but you more than make up for it by completely (or at least partially in certain setups) removing the cable. I'm not talking about those wanna-be executive type ear-usb sticks before you look at me crazy. Personally I use a semi-bluetooth setup which allows me to clip a tiny bluetooth adapter to my armband and use a pair of cheap earbuds with a short cable that plugs into that instead of my phone. Lets me keep the bulky SGS3 safely in my pocket without any risk of snagging the cable on something or dropping the phone while changing tracks etc. It also makes phone calls when i'm out running a lot easier. I no longer have to hold the phone on my head with one hand while trying to run, or out in front of me like a retard lol. If you're confused by what I mean, it is something like this, but a more expensive samsung model I couldn't find after a quick search: http://www.amazon.com/GOgroove-BlueSENSE-Bluetooth-Wireless-Streaming/dp/B009XJZ9VY/ref=pd_sim_cps_6Edited by Zero4549 - 6/21/13 at 3:27pm