Boxer grow bags are made from recycled water bottles. These are extremely affordable. I buy mine at the local hydroponic store but they are available online as well.
https://rootpouch.com/ and
http://rootpouch.com/products
"All of our fabrics are BPA free, and resistant to UV light."
Here is an example of one online supplier's pricing. Note that the bags 5 gallons and larger come with convenient handles.
$1.00 — One gallon, each
$20.00 — One gallon, pack of 25
$1.50 — Two gallon, each
$30.00 — Two gallon, pack of 25
$2.00 — Three gallon, each
$40.00 — Three gallon, pack of 25
$3.00 — Five gallon with handles, each
$25.00 — Five gallon with handles, pack of 10
$3.75 — Seven gallon with handles, each
$33.00 — Seven gallon with handles, pack of 10
$4.50 — Ten gallon with handles, each
$40.00 — Ten gallon with handles, pack of 10
$7.00 — Fifteen gallon with handles, each
$56.00 — Fifteen gallon with handles, pack of 10
$8.00 — Twenty gallon with handles, each
$64.00 — Twenty gallon with handles, pack of 10
$9.00 — Twenty-five gallon with handles, each
$70.00 — Twenty-five gallon with handles, pack of 10
$10.00 — Thirty gallon with handles, each
$83.00 — Thirty gallon with handles, pack of 10
$12.00 — Thirty-five gallon with handles, each
$95.00 — Thirty-five gallon with handles, pack of 10
$14.00 — Forty-five gallon with handles, each
$110.00 — Forty-five gallon with handles, pack of 10
If shopping online, please check for the best pricing as some folks (such as 'Heiroom Organics') think 'organic' growers want to pay double the normal price.