Like you, I found myself without a "solid" foundation in my stash, so after selling a set of cookbooks on eBay, I treated myself to purchase several FQ bundles of solids from Keepsake quilting. They gave me both the "workable" amount of fabric and the gradation I needed across the color spectrum.
The tone-on-tones I have on hand are the white-ivory-cream-VERYLIGHT beige range, with some blacks, reds and greens (think Christmas tones).
I found myself hanging onto fabric types just so I'd have them, and then realized they were no longer that attractive to me any more - so I passed them on through various FQ and scrap swaps, Secret Santa/Secret Sister gifts and Mystery Raffles at my guilds. See my new topic on MYSTERY RAFFLES, which I'll create after I send this out ...