There are some tech levels which are rare to get, but are useless outside of tech disks.
Examples include:
Anomaly cores have a tech value of 7 in one of a random few categories such as Engineering and Power Manipulation, which can get you to level 8.
Certain Abductor tools can also get you to level 8s, such as Materials 8 and Biology 8.
Nuclear Operative items (some of which, namely Donksoft weapons, can also be gotten from Sol Traders) generally have Illegal Tech level 6.
Of course, these high tech levels have no real reward for achieving them.
For anomaly cores, it could be made a choice between getting a Phazon or some fancy new tech.
Alien tools are already enough of a reward, so Abductor stuff isn't as big a deal.
Things that require Illegal tech cap at requiring Illegal 3.
I have some ideas, but feel free to make your own.
Power 8 could let you make the artificial equivalent of a yellow slime cell.
Materials 8 could let you make Synthetic Diamonds from a large amount of plasma.
Biotech 8 could let you make Artificial Xenomorph Organs (except egg-laying of course).
High Illegal tech could let you make e-shields(which would not be lockboxed, as teleshields are not), and/or "energy broadswords": they are still lockboxed, and they also have a larger handle than normal eswords, preventing desword creation, and also being unable to be stored in pockets.
