I've just been referred as a new customer by my father-in-law to sky.
Initially they offered us each a £50 M&S voucher, plus an 8Gb Ipod touch for my father in law (subject to stock).
The £83.50 is the package price for the first 6 months, it goes up to £88.50 after then.
I took the whole bundle - sky world, plus ESPN plus sky talk and line rental. Initially they said free installation wasnt available with the other offers, but soon backed down, I also managed to get the standard broadband upgraded to sky unlimited for half price for 6 months.
I know all these offers have been mentioned individually, but ive not seen any post with them all at once....
Good luck haggling!