theres no "average" cost. there is such a wide range of prices and equipment to even attempt to justify an average price range.the best thig you could possibly do is sit down and write out every last piece of equipment youll need, complete with prices. and dont be afraid to give yourself some high/low end options. Also, if the budget allows it, i would go with something a bit bigger (27/30/40b) !0g tanks make great nano reef tanks, but they require a very stble and consistant experienced keeper. Not saying you cant do it but itll prob be a bit overwhelming. try your hand at a bigger size first, they are more forgiving
