At an imaginary store that sells fairy tale items. You might check Diagon Alley.
impossible
No, I can not buy you a mermaid's tail.
Where you can find a mermaid tail but cheaper is, walmart.
it is imposible
in england
no sry the h20 tails cost a $1,000
It is different for every tail
Sorry to say you cannot. Mermaid tails can be made for about 70 dollars for the fabric and the monofin of your choice. Prices range when MAKING one. I suggest that, because the easiest buy I've seen was mermaid tail on Ebay. They have large selection colors, but the price is about 110 dollars. Look up "How to make a mermaid tail" on youtube.
Mermagica is the best place to get a mermaid tail or, if you feel crafty, just go online and search 'how to make a mermaid tail' and make one yourself.
magictails.de
Anywhere that has a costume
Well at Mermagica.com you can buy a tail for $100 +shipping or you could make a tail its way cheaper!