IMO Aquablox are ok for a vehicle kit or something like that, but silly for significant quantities at home. The usual advice seems to be get some 7 gallon aqua-tainers from REI and fill them with tap water, rotating the water every 6 months. Add a few drops of bleach per gallon to stop stuff from growing in the water. The aqua-tainers are cube shaped, sturdy, and stackable.
For larger quantities you can look into 55 gallon drums, flex tanks (
www.aquaflex.net), or other types of above ground or underground tanks or cisterns. There is a dealer on ebay who has a wide selection of plastic tanks up to 10,000 or so gallons. The underground ones in the 500-1500 gallon range seem quite practical. The 500 gallon cistern is a sphere about 5 feet in diameter with an access port on top--just dig a hole in the backyard, install the cistern, and fill it from a hose. I'm in a small urban apartment with no backyard but might put a 60 or 110 gallon aquaflex tank under my bed.
Finally if you have the yard space, you could put in a swimming pool or a small pond as a dual use facility.