I am starting to feel this item being too strong.
Most AP will run it, its good for some but it gets to a point where its a must get for AP. Very good armor and a invulnerable buff (which is further buffed in s3 with artifact mastery)
The downside is, it can't be rushed. But since games mostly do last longer then say 6 months ago (revive meta), early game does not play as major a role, and item like this is very strong
Perhaps lower the armor / static effect very very slightly (it doesn't need much nerf, but needs something i feel)?
Wooglet is definitely very gold-efficient, and is really quite possibly the best item in the game from that perspective--and it's meant to be that way, as others have mentioned. In fact, the next patch will give it a much simpler buildup--I think I've mentioned this on the DominateDominion chat before: 2x Blasting Wand + Chain Vest.
A lot of this is because of how AP champions are balanced; Deathcap is such an ubiquitous buy (or was, before everyone started stacking pen) on Summoner's Rift that AP are effectively balanced with the expectation that they'll have Deathcap's AP steroid. Of course, on SR you generally have a lot more room to maneuver, wards, blue buff, and elixirs to fill in the weaknesses. Dominion (and TT) are very different scenarios.
I'm still not quite happy with AP itemization. BFT is taking over, but it'll receive several changes as well (3950 gold, Kage's + Codex + Haunting Guise). There's definitely room for one or two more interesting items... we'll see what happens