ordering online it's all about the warranty policy if things die. I think foster and smith by far has the best. I ordered my cleaning crew from them (etropicals, not live aquaria--prices are actually different on the 2 sites) and was very pleased.
As easy mentioned, or started to, a naso tang is not appropriate for a 24 gallon--it'll very quickly outgrow. In fact, NO tangs are appropriate for tanks under 50 gallons.