What kind of clubs are you getting in to for £3? It's not the 90s anymore.
A grand is reasonable for a week. You will spend it easily though. If it's your first time in Ibiza and you've got plenty money then fuck it, just spend it. You might come home thinking "fuck, I've spent £1500" but you'll also come home thinking "fuck, that was amazing!"
Ibiza is heavy good. I want to try n make it out in September but I doubt I'll have the money. Choking for a Space Sunday.
Do you already have an idea what clubs you want to go to? When are you going? Sorry if this has been covered, can't be arsed reading back through the thread.