Going to go with LA -0 on the psi-crystal without propulsion for obvious reasons.

WITH propulsion, something more interesting occurs; no racial HD and full construct traits is something to consider. Net abilities are -10 and that Str means you need other means of carrying gear, since your capacity is at 1/4 after applying your meager strength; you have to put in at least some points there simply to heft most items one at a time. That eats directly into the non-type bonuses you get besides Hardness, which is your Dex and speed. Having such a short visual range is a big penalty, and prevents you from reading, discerning color, and despite being telepathic cannot discern invisible or ethereal.

Overall I am torn; the size, DR, Dex and Construct traits while dumping Str screams caster, but you are -4 Int and +0 Wis and Cha. You are blind past 40 ft and have a large number of obstacles to hurdle within that range. The crux is that you could have full Construct traits, normally a capstone or possessing a hefty RHD/LA price tag, by instead taking a bunch of penalties. And the effective DR via Hardness is serious, because it will stack with any actual DR you gain.

All right, I will tentatively call this LA +0 with propulsion active. The Hardness and Construct traits are enough to build around with a Wis/Cha caster-ish build, while the monstrous penalties and limitations more or less balance it out in my view.