If this type of thing piques you interest, there is a vibrant aquaponics community with many forums eg. [1] and designs using all sorts of off-the-shelf parts.

IBCs and blue plastic drums are generally the "go to' solution [2] as they're made from HDPE, although some are made from plastics that are not considered food safe as they use mould release agents during the manufacturing process which are toxic (no reference for this at the moment, sorry).

Just be aware that generally you need A LOT more grow bed area than you would think to be able to efficiently use the fish tank volume. You can pack a lot of happy fish into a given volume of water.

Also, the general consensus is to use course gravel (20mm) rather than sand, as sand can quickly become blocked with organic material.

[1] http://www.backyardaquaponics.com/forum/

[2] http://ibcofaquaponics.com/

[EDIT] Also, you'll want to keep the sunlight off the fish tank, because once the nitrogen level starts to rise [3], the algae will go nuts in there. I learned this the hard way.

[3] http://www.backyardaquaponics.com/information/the-nitrogen-c...