afaik, ufo:ai autosell only applies to alien items that are researched, and researching junk has low priority as research is limited (duh), so most of the junk still needs to be sold manually and autosell is limited to alien light armor (needed for nanocomposite) for a looooong part of the game.
lol, i guess the best solution would be to merge the ufo:ai and x-force games : )
x-force has excellent storage and production management, soldier filters, soldier hiring prices, and some other very nice features, i think those features might at least be worth looking at.
if i remember correctly, they had not only 'number of items to keep in storage' but that also applied to production of items, something like 'produce this item if there is less than X in storage'.
or, certainly you could assign a small number of workers to produce ammo (slowly but) infinitely.
hopefully some no-life coders suddenly appear and we get something similar in ufo:ai.