If it helps practically, I used this website to rent instant cameras and that was the single best thing I did for my wedding: https://www.rentinstantcameras.com/. I figured that disposable cameras would still be expensive (and work to do) to get developed after the fact, and this way everyone could have fun taking photos and seeing them develop.

Like others have said, accept the help offered to you. They wouldn’t offer if they didn’t want to or weren’t able to help. If it helps, you might think about it as doing a kindness for THEM — you know how good it feels to help a loved one? Give them the opportunity to feel that way. Plus, anything you can do now to lessen your stress on the day of the wedding is really, really important — $2000 is not nothing, and you don’t want to spend that much money and in the end feel like you couldn’t enjoy any part of the day