Those "outdated" lenses still work fine for normal usage, too.
Just bought a EF 28-105mm f/3.5-4.5 for under $70 and replaced my too big and too heavy 24-105mm L. Also bought an old EF 100-300mm zoom for about the same price. The IQ is really good for non-pixel peepers. Both lenses have lens correction profiles, so they work very well on my 6D. Sold the "L" on Ebay. So now I have two lenses (I used to have only the one) and made over a couple hundred bucks as well. For those with limited funds, looking into the older mid-quality lenses may be a good idea.