What if the starting items for supports all had a stacking mechanic that other items would use...
...to grant extra stats?
What gives the stacks could be anything (but most likely something in relation to your lane partner), like every time he gets CS, or every time you heal or shield or buff a team mate, or anything that is an actual balanced way to do this. The stacks would be stored on the starter item but other items would grant extra stats in relation to those stacks, making for more gold efficient items.
That way you can have items in the game that are cheapish and give average stats for most but give great stats for the support class.
If you make these items be the in-between items for the other classes it won't affect them as they'll use them until they can upgrade those items to the end items, supports would keep the in-between items and the items would get stronger over time without extra gold input as long as you can get your stacks.
Does this sound like a good idea?
