I'm afraid I don't have the answers to all of your questions because the last time I was in Ibiza was back in 2005. I am confident to say things have changed significantly (for the most part anyway.)
But to answer your questions:
- How did you plan it? - I didn't. I was already in London and Paris and I found a cheap flight on Air Berlin, booked it and went. Everything I did was spur of the moment, from hotels, to clubs/bars etc. I did do some reading on Ibiza Spotlight which I found very helpful.
- Which clubs did you visit? - I ended up going to Pacha, Space and Es Paradis.
- How much did it cost? - I went at the tail end of the season so I was there for the closing parties. By that time, most of the tourists have gone home so hotels were cheap'ish. I splurged and stayed at the Pacha Hotel in Ibiza Town when it was relatively new for about $125 Euros per night but that included cover to their club, breakfast and drink vouchers.
When I was in San Antonio, I stayed at I think what is now known as The Bellemar hotel (sorry, I don't recall exactly.) GFunk and his friend stayed at I think the Marfil Hotel which is a lot more central to San Antonio. Just keep in mind during the times you are planning to go, it's full-on tourist season so be prepared to pay tourist prices everywhere you go!
Make sure you learn some basic Spanish. The locals there really do appreciate people who do try, even if it is saying hello, please, and thanks. They have been dealing with flocks of British and German tourists who don't try whatsoever to the point where menus will have more than 3 languages. Have fun and stay safe!
