I'm hesitant to tell any couple that they MUST add something to their wedding budget, but I feel stronger about this than I do about flowers, favors, or even food. The you'll-thank-me-for-this thing you should definitely make for in your wedding budget? A professional house cleaning 1-2 weeks before your wedding.
If you're going to have friends and family staying with you before the wedding, or if you're getting ready at your place, you're going to want your house to look nice. And maybe you keep your home spotless all the time, and having to tidy up right before your wedding won't be a big deal, but in our experience, cleaning is an annoying chore that you and your fiancé aren't going to want to bother with when you're in the final stages of prepping for the big day. And even if you aren't going to have guests at your home the week of your wedding, having a clean space will help you feel relaxed and organized (and will be extra nice to come home to after your wedding and/or honeymoon). So add another $100-$200 for a deep cleaning to your budget now and you'll be so glad you did as your big day draws near!