Sources say JUSTIN TIMBERLAKE and JESSICA BIEL are throwing themselves a $6.5 MILLION wedding in Italy this weekend.  (--At least one source claims it's going down TODAY.-Friday) 

--Even though that's probably not much money to them, it's HUGE, even compared to other celebrity weddings. 

--TOM CRUISE and KATIE HOLMES "only" spent $2 million on their wedding. 

--The wedding of MADONNA and GUY RITCHIE was a mere $1.5 million. 

--And BRAD PITT and JENNIFER ANISTON shelled out a measly $1 million on theirs.  (--This is all speculation, but E! Online talked to some experts who suggested where all that money could be going.) 

--Meanwhile, Jessica and Justin threw a pre-wedding dinner party at a beachfront resort in Puglia, Italy on Wednesday that included fireworks. 

--The guests included Justin's "Saturday Night Live" buddy ANDY SAMBERG.  (--Check out some pics here.)  (Us Weekly, Daily Mail)