Start up cost....Say you already have the location and looking to get the large or main things you need for a venue  to hold 250 people.

One of the places I found online is : Chairs 4 Less : http://www.churchchairs4less.com/

(500)  White Resin Stacking Chiavari Chair               $34.99 each  total  $17,495.00

(30)  96 x30 long rectangle tables (reception tables)  $250.98 each total $7,529.70

(30) 72in round tables (reception tables)                     $258.98 each total $7,769.40

(1) Half Moon table (cake table)                                   $97.99 each   total $97.99

(2) Buffet Tables                                                             $ 140.98 each total $281.96

(2) 3 gallon drink dispensers                                         $290.99 each total $581.98

TOTAL: $33,756.03

American Discount Tableware     http://www.americandiscounttableware.com/

China (plates and bowls) Flutes, Drink glasses, and Cutlery     Total: $3,844.23

Table Linens                                                                                  Total $3,565.08 

GRAND TOTAL: 41,165.34

There is still many things to be added to this list, but these are the larger things or the necessities for a venue.