Eileen, most BS rent their wedding gowns.
the difference for price is whether you want a Made to measure (MTM) or Over the rack (OTR) gowns.
price for mtm will be more expensive, as they design the gown based on what you want eg, the color, material, design, blings, cutting. generally package includes wedding gown and evening gown, mens suit, makeup flower bouquet and ranges $4k-$6k. eg Silhoutte, Bridal veil, the wedding present, Dang...etc..
generally, most BS in tanjong pagar offers OTR gowns (means a few brides might wear the same piece) with photography package of 25-30 photos included. it includes the above gowns n suit but you choose what is already designed over the rack. price range is definitely more affordable $3.5k up.
basically, designer bs will be more costly...so it really depends on what you wish and budget you are prepared to pay..=)