Hi, Belinda!
I completely understand your hesitation to spend the extra money. It is a bit of extra money which you could put toward meals or a souvenir, instead. I hear ya'!
We've done breakfast at Cinderella's Royal Table with my daughter having first visited Bibbidi Bobbidi Boutique as well as without it. While it is very special to dine with the princesses after having had a royal makeover, you can surely add to your daughter's princess dress and crown a little extra sparkle without the expense. Consider some glitter for her face (pixie dust!) and sparkly nail polish, too. Perhaps a special necklace or bracelet and she'll feel oh so special, without the added expense and fuss of the makeover at BBB.
From your earlier question, I can see that your princess will be celebrating her 5th birthday at CRT; I'm sure the fuss of her birthday, and wearing a special
Birthday Celebration Button (complimentary, from any Guest Relations desk) will make this one birthday she'll always remember. (And she'll never miss the boutique, either, since she probably doesn't even know it exists! :-) )
Have a great trip! Be sure to send more questions as you think of them; we love to help!