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.