I could be wrong but I think it was confirmed in a few places that we pay no more than 20ish, and after that there is possible add ons up to 28M.
but, 30M no.
Yeah, I think it was in the interests of all parties to publicise the full potential value of the deal (Chelsea - "look how much we got!" Everton - "look how much we spent!") but I recall one or two links posted on this very site that seemed to credibly break down the cost of the deal, including flat staggered payments of somewhere between 20-24m with the rest payable upon certain conditions being met.
I do wonder if Chelsea got a sell-on clause, purely out of interest.