Let me ask this:
If they were to offer the Tier 7 ship parts in one complete package for $5 on the CM and also offer it from a Vendor in game for 500,000 credits, would it still be a problem?
For me that would be almost as bad as the current implementation. This would still totally kill all the sense of progress and achievement (and challenge from earlier tiers).
Now if you could only buy / use the parts only after completing the earlier missions in combination to your suggestion might be a decent solution. Offering few of the items only as prize for completing certain missions and maybe one or two only with comms would be even better.
Somehow it seems Bioware completely forgot the basic rules of keeping a game interesting and are only going for a money grab. Buying better gear with grinded creds or a credit card is definitely the least interesting way to progress in a game.