Craftsy, I realized it would be better as a blog post with links.
Thanks for asking! There are 3 types of fabric I use in this pattern. The main exterior fabric I like best is home decor weight cotton. If you like Waverly fabrics, there are a lot of good choices at JoAnns. The rose fabric I use is Waverly Norfolk Rose. Also any of the 45" wide home decor fabrics on bolts at JoAnns work well. That is where I found the black and white houndstooth - and I bought all I could find in Washington and North Idaho. The fabrics in my main photo on Craftsy are all Amy Butler Fabrics. At Westminster fabrics you can find modern designers like Joel Dewberry, Ty Pennington, and Amy Butler. They all have home decor weight cottons that work well in a variety of prints. The great thing about using those designer fabrics is they have coordinating/contrasting fabrics in quilting weight to use for the strap fabric. You can use quilting weight for the main fabric as well, but I do like the home decor weight better for it's durability. The bag shown above has Amy Butler home decor fabric from her Lark collection paired with Kaffe Fassett's paisley jungle in tangerine.
When I quilt the main fabric, I like to use a premium quality muslin for the back. That becomes the inside of the bag. I don't use fashion fabric for that because you don't really see it. You need a high quality fabric there though because it is getting used as you load and unload the bag. My favorite for this is Kona premium muslin. I have linked to the 44 inch wide, but it does come wider if you are making more than one duffle. A lot of my links take you to fabric.com. One of the things I like about ordering from them is free shipping on orders over $35. If you ordered all 3 fabrics together, it comes to about $50, so your shipping is free.
I get my jute webbing at JoAnns. I like the quality they carry. I have ordered it elsewhere, but I did not like it as well.
JoAnns is also where I go for the batting I use. They don't have the one I use online, but it looks like this one. The one I use is Soft n Crafty batting in the 8 ounce. The one online is 10 ounce which would be too hard for you to work with. I get a lot of questions about the batting. Yes, you can use any batting you like. I suggest if you are using black fabric that you use black batting. I use the 8 ounce (and after making hundreds of duffles I still like it the best) because it makes the bag stand up on its own while it is empty. I need that for photographing the duffles. If you would rather fold your duffle and put it in the linen closet when you are not using it, you can use something like warm and natural for the batting. The very first duffle I made was with warm and natural and I still use the bag. It is holding up perfectly well to tons of use. It is easier to sew with the thinner batting. If ease is a factor and you don't need photos, use the lighter batting. JoAnns has loads of coupon and sales. I never pay full price there. Usually, the prices I pay at JoAnns are lower than I could get wholesale.
I hope this helps you! Please feel free to ask questions.
Here is the post with the quilting plan I use:
Quilting the duffle fabric