Looks like the super fight could generate £270 Million ($400 Million)

"The money that will be generated by the welterweight title unification fight between Floyd Mayweather Jr. and Manny Pacquiao -- already expected to be a slam dunk to break every revenue record in combat sports history -- is growing by the day and could easily surpass $400 million (£270m).
The live gate for the May 2 fight at the MGM Grand Garden Arena in Las Vegas will generate a staggering $74m (£50m) from the sale of a little more than 15,000 tickets, Top Rank chairman Bob Arum, Pacquiao's promoter, told ESPN on Monday.
That is almost four times the gate record of $20,003,150 (£13.4m) generated by ticket sales for Mayweather's light-middleweight unification fight against Canelo Alvarez, also at the MGM Grand Garden Arena, in September 2013."

Floyd Mayweather-Manny Pacquiao showdown could make a record-shattering £270m | Boxing News | ESPN.co.uk