For a family of three unless you are coming from an international location WDW really doesn't have to cost $3-4K. I'm not sure how long you intend to stay, but perhaps make the first visit a shorter one, 3-5 nights rather than try to spend 7-10 or so.
Find a character or story that she likes. Is she a fan of Playhouse Disney? Then let her know she'll have a chance to meet those characters, dance at their show and even have a meal with them if you book that character meal. Does she like the Princesses or Minnie? Promise to let her dress up like the princess or Minnie. Some of the most magical moments at WDW are with the character interactions or reactions to seeing them.
Many kids don't like the loud noise that goes along with the fireworks, but the parades are fun and not loud.
I really wouldn't focus on the rides at WDW, esp for a 5yo. The character meetings (in the park or at a meal), shows, parades and now games all offer some wonderful ways to enjoy your time at WDW. Honestly if she won't ride that gives you and your wife license to ride.
We took my nephew at 5 and he had a ball. He was already OK with rides, but there were also plenty of things either he didn't want to ride or we didn't try to put him on. His big phobia was 3D, but we really didn't realize this before the trip. He screamed and spent our time at Mickey's Philharmagic in grandma's lap, back to the screen. He rode BTMRR, but didn't like it and honestly neither did I.
We just returned from a trip, he's now 7yo and surprised me with some of his requests: We did Haunted Mansion for the first time during the
MNSSHP. He seemed a bit scared during the ride, but he asked to return to MK to ride it on our final morning of the trip, shocked the heck our of me! He rode Pirates of the Carribbean and he absolutely loved Soarin' and Test Track. He refused to do the water rides (Splash Moutain, Kali River Rapids, but indicated he might be willing to try them next trip). He made huge ride strides this trip and if we hadn't taken him for the first trip, we never would have seen this "growth".
My gut says do two things:
1. Go and enjoy so much of what WDW as to offer, not just rides. As she gets comfortable with WDW I think you'll have better luck getting her to try new things there. To me WDW isn't like an amusement park. It has a much more magical feel and the pace isn't so harried.
2. If you are really concerned about the cost, shorten the trip or change your resort to bring your cost down. A family of 3 really can have a nice trip to WDW for under $1500 plus airfare or driving costs. Don't buy waterpark option for a first trip; the WDW pools are really nice and the WP would be overkill for a child that young on a first trip to WDW.