I have found calico on Etsy. I just put vintage quilt fabric in the search box, and its amazing how much vintage fabric is still around. I've bought quite a bit from there, too.

I going to try that right now!!!!!

One thought that occurred to me is that you may need to artificially fade new fabric -- even if it is an exact match -- to the quilt. All dyes are subject to fading, primarily from exposure to light. I would err on the side of caution here, and expose the new fabric to sunlight for only one hour at a time (no folds, or you will get fade lines!) until it is only a little bit brighter than the old fabric. I think this is safer than multiple washings of the fabric to get the same effect. Sunlight would be less harsh than multiple washings and dryings.

there is a store in Bozemam Montana that all they have is reproduction fabrics not sure if this will help you but think maybe you can google them at reproduction fabrics if you can't pm me and I will try to get better info hope this will help

Our LQS carries vintage fabrics. They have maybe 60 blots of VIP. They do mail order so if you IM me I can give you the information.

I found some wonderful 30's type fabric at Connecting Threads. I was working on some Dresden Plate blocks and needed something to set them together and the fabric I got there was wonderful. And only $2.95 per yard. Good quality fabric at a good price.

I wish I knew exactly what you were looking for because I have some I would share. I have found a lot on Missouri Star and other sites that are great. Just google calico prints.

Here are my calicos..could they work? Only the red w/white is VIP. PM me if they could work.

You might try googling "vintage VIP calico fabric". Maybe you'll get lucky. I've never done business with them but thefind.com has some older calico.

Sorry this doesn't help you but if anyone is looking for calico in the UK Whaleys in Bradford have a good selection. They also have 108in wide cotton percale which dyes beautifully and is lovely to sew with.
www.whaleys-bradford.ltd.uk