I usually hit the sale room at the fabric store and purchase backing fabric there. It doesn't have to match the front.

Walmart has backing fabric that I think is pretty good. Take a look there.

I have even used duvet covers. There you have two sheets worth - I look for them during sales. I even used a lovely used duvet cover that was a white with a white design when making one of my quilts as the background fabric. It is one of my favorite quilts.

With the majority of my quilts, I dig into my scrap fabrics and put together a back. Very often, I even just make a quilt top for a backing. It works fabulously.

I also would go with marshalls.

I just made a scrappy for my daughter. I used a navy blue for sashing between the squares, then for the back I pieced several of my yard+ pieces of blue prints for a backing. Since I made stripes it looks reversible.

I love the scrappy, or even structured block backs and use them when I can for throw size or below. Guess I'm just not wanting to put extra work into this queen sized. But thanks so much for the suggestions.

Fabric.com has backing fabric on sale!!! With the retailmenot coupon, I was able to purchase for less than $7.00 a yard and with free shipping!!!

Thankyou for the heads-up re marshalldrygoods.com. Great selection of colours. Now to find out if they'll ship to the UK...

If you are quilting it yourself, you may want to consider a cotton sheet with a low thread count of 250. Recently, I used a king size sheet for a queen size quilt and it worked out perfectly without any problems with machine quilting. Walmart carries 100% cotton sheets that are sold individually ( rather than having to buy a set of sheets you can buy only a flat sheet) . A king size is around $15.