I got mine, last time I ordered, from a guy named glassaholic1031 on ebay. He had about the best prices around and very reasonable shipping. Couldn't find anyone locally who wwould sell me anything larger than the size you described, so it was about my best option.

I buy it in 4 cu.ft. bags at one of the local Pikes Nurseries.
Cost about $17.00 per bag. You are probably not near a Pikes, and on the web, the people at vermiculite.com suggest asking a local nursery to help you. Sometimes, if you are willing to purchase several bags in one purchase, they will special order for you. I considered buying online before, but found shipping costs made it too expensive.

Hope this helps.

Call around to see if you can find a local nursery that purchases products from GroSouth. They are a wholesale supplier of nursery, landscape & agriculture products, with warehouses in Atlanta and Montgomery & Dothan, AL.
They sell Perlite & Vermiculite(medium or coarse)in 4ft³. bags, plus the smaller size(20qts).
The suggested retail price for either product is in the $12-$13 range(4 ft³). (plus Retailer's gouge factor, of course!)
Good luck!
Rb

Ace Village Hardware has large bags of Vermiculite in right now, and I've ordered pearlite - they come from GroSouth.

GGG

A feed and seed store should have it. I believe I remember my fiance seeing a 50 pound bag at one recently.

Diana

Macon Feed and Seed on Emery Hwy, Macon, usually has perlite, vermiculite, in the long 4ft bags, around $12 bag last time I purchased and will order if they don't have it. Minton on Pio Nono sometimes has the larger bags also. I have also seen the large bags at the feed and seed in Forsyth.

Lisa B.

Looks like the Pikes at Lindberg has 2cubic foot bags of the coarse vermiculite

Location: 2410 Camellia Lane NE, Atlanta, GA 30324