We considered every last tiny detail in our budget -- and still ended up over 25% after fine tuning all the details.
Here are the items we included -- some things which we had initially overlooked when first budgeting...
travel (if u can afford to prepay the deposit for 10 rooms up front, most agents will allow a group booking...then you may be able to get your room plus other perks or free....which could save u a few bucks)
photog overnight room fee (book at the beach hotel EARLY -- when they run a special)
save the dates (u could email these to save $$ - and then send out an early invitation like a boarding pass or combo save the date/invite)
cigars or cigar roller
additional pp over 15
cocktail or extra hour 13pp
generator (90 per hr)
cards for bms and parents
babysitter for ceremony
thank you cards
make a spreadsheet and start plugging in the numbers.... hope this helps!