This mod replaces the jack with an inline female stereo connector. It can wiggle freely in all directions. Whether or not it looks good is besides the point of correcting a design flaw.
The approach I took should even work for other audio players or similar devices, although I could understand how the implementation may be bothersome to users: the combined length of jack and plug is as long as the c200 itself. It's still portable IMO, especially if you've put a lanyard on yours, too.
I've documented this only after having already modded 1 of 2 sansa c240s I own, so some of the critical steps may be unclear and/or difficult to reproduce, and I overall feel this method is slightly difficult to execute, given the YMMV factor; it only took me 2 years to even consider trying. At any rate, I plan to mod the second sansa later. If it turns out successful, I guess I will revise my advice to sound more optimistic.
I recommend you read the entire instructable before starting, and take a close look at the original 1280x800 images if at any point things are unclear. The precision required for this mod is beyond my preference, especially the soldering involved.
Step 1: Geekspeak you can skip: more background info and design thoughts
A possible ideal alternative to the jack used is one that is essentially like the neighboring, springy battery connector, which also has three terminals (which is why this solution seems obvious). The jack would snap or friction fit into the casing, and make contact with wider traces on the PCB once assembled. All stress would be taken by the shell, with springy room to buffer against the PCB. Alas, the level of precision required for this is best done by professionals, and even then the space required by this suspension system could be difficult to allot in such miniature device designs. It's actually more likely an issue of this complexity incurring more cost, but I digress.
The elegance of my mod is that the replacement jack is virtually decoupled from the PCB so it shouldn't ever fail unless the jack is ripped off, which is probably this implementation's greatest obvious weakness.