Generally whining is pretty bad. IMO, most cases involve more work than a T5 is worth.
Figure if it grinds or pops out of gear, a rebuild with parts and labor is about $550 give or take a few bucks.
Nothing in the small parts rebuild kit is going to fix a whine more than likely.
So now you get into replacing major components of the trans, which are generally very expensive.
I had a trans that was whining, hanlon quoted me $850 to fix it.
So i got a $100 trans that was popping out of gear, and had it repaired, total was $600 (including the trans).