The only expensive date to my avail would be with Rae when she gets her outfit - but if I'm not mistaken you are not even supposed to cover for it since there's some storyline attached to it
Can't remember how much the glasses cost for Cait but I had some 90 bucks at the time and it sufficed.
I'd assume the game won't let you do those scenes if you lack the funds - and if you start fresh you can pretty much blow the time searching the wardrobe until Day 15 as the story won't continue until then anyway (would have been proper to have that hint in-game btw.)