It is expensive to collect fabrics if you buy in retail quantities (FQ, 1/2 yd, etc). My wife and I collected half yards for a few years before we were able to make the I spy quilts we wanted. We would buy a couple of fabrics each time we made another purchase and store it all together. When we got 130 fabrics we cut them into 5” squares and made them into 24 kits.

I know you said you’d like to have them all together at once, but we never found a source to buy kits ready to sew, so that’s how we did it.

Good luck.

I may not have made myself clear on my previous post. The I Spy group on groups.io is active. They do one swap per month (excluding December). Most of the time, the swap will have a theme. They do ABC about twice a year. sometimes they will do one with a black background, some years they do a boys or girls swap, things that go, beach, camping, etc. They are on facebook as well.
bkay

Shop the remnant bins and thrift shops. You can also use a few polka dots/plaids/Christmas items. Think "outside the box"