best quick smoker is the kilwell box . cheapest is galvised box though these generaly rust out over time. Stainless steel will last better.As you say you need to watch on” trademe”.Another way is to have a biscuit tin with sawdust in bottom cover with tin foil and put holes in it and put a lid on.One I have seen lately was an old round bbq with lid ( charcoal old type) with rack sat on a bbq.For other suggestion get a copy of ” Kiwi Smoker” book appox $10 as this has methods and ideas aswell as recipes