I found some 6" and 12" round and square tube smokers for less than $20 delivered from China these are a great price.
They look like A-maze-N copies.
They are great to add smoke to your gas bbq. Especially the ones that don't have the traditional burner where the trick of wedging a wood chunk near the burner doesn't work.
http://www.ebay.com.au/itm/New-Stainles ... ZaN7-3_3NA