I love the bottomweight knit fabric at chezami.com (read the descriptions carefully so you know if it is top or bottom weight, but their cotton lycra would work great for bottoms too!). Fabric fairy has great basics all the time, and they are super helpful on the phone or email to help you decide if it would be appropriate for shirts, leggings, matching colors, etc. Fabric.com has great prices but the stock rotates so you have to keep checking the new arrivals to find what you need, but with free shipping and lots of discounts, it’s worth it! Hope this helps- Katja
PS You should be able to wash and dry any cotton knit fabric as long as you have washed and dried it thoroughly – at least 2-3 times W and D- before you cut it! A lot of it keeps shrinking after the first wash!