My question is about playing support in competitive environments. It's extremely common (indeed, standard) to see a support start with a Faerie Charm and some Sight Wards so that they can later build to Philosopher's Stone. It's also not uncommon to see Heart of Gold. Recently, I've even been getting Kage's Lucky Pick. One can even imagine a situation where Avarice Blade would be viable on a support like Blitzcrank (if you're intending to go more AD support than a full on aura items build).
How many gp10 items is "too many"? What I mean by this is: at what point does it become counter productive to keep getting items for the gp10? At what point are you getting worse returns than if you just went ahead and got that Aegis of the Legion or Zeke's Herald or whatever?
EDIT: By competitive play, I mean someone who is doing ranked games seriously in order to improve their Elo and hit 1900+, rather than someone who is just messing around in a Normal building AP Sona. This is someone who is genuinely serious about understanding the meta game in depth and wants to improve his skill at the game.