create a moth laden with stuff in a random sector with or without bots, make it explode and have the user retrieve only a specific commodity from the wreck.
since cargo crates time out there would be an advisory before the mission. have the wreck be of random origin, rescuing the pilot nets you some faction stat up from whatever nation/corp he comes from.
any other commodity from the wreck is gravy and not needed to complete the mission.

Even better, have there be a drifting, damaged moth which you must destroy to salvage. Solves the time-out problem.

there's been suggestion of debris fields before for a number of different purpose.

one was to delimit and augment's the user's perception of danger upon entering grey space.

another use of that was precisely that, warsong: salvage missions and special item sarch/recovery.

another was for the hive bots. imagine they roam around the sectors rather than just linger in one sector. they'd be real scavengers, gathering ship carcases to build up their hive. the more ship carcases in a sector, the more these hive bots show up.

i think space is way too clean considering the number of ships that go pop.