I purchased a lot of old and worn SAK's on eBay for around $7 each. Some only needed some cleaning, and a spring or toothpick and tweezers, maybe some new scales (all which I keep on hand). Scales that are just scuffed up shine up super nicely when gone over with some Flitz, by the way.
Some of the knives had bent, broken, and worn out blades. I sent them back to Victorinox, and for a few of them asked nicely if they could replace the main blade with a serrated one. I strongly prefer a serrated blade for most of the work I use my EDC for (cutting twine, boxes, and fruit). They were kind enough to accommodate me. Here is my new favorite EDC, which is an old grooved corkscrew era Champion with a new serrated blade:
When I got it back I put some plus scales on it, even thought they replaced the scales before returning it.