Good idea?

I don't have any of JKCK requirements. They are all 3 star and gear 1 (besides Merrin who is 7 star and low gear). I was thinking of just buying a carbonite LST for all of them, since those characters don't seem to be a requirement for anything else and I also don't see myself using them for anything and it would save me a lot of kyro. Only annoying thing would be the need to farm a lot of shards to get them all to 7 stars.
So is it a good idea? Or are any of them actually worth considering to be used for something else too and therefore might be worth using an aurodium LST instead?