Cheer up, you will only need 4 posts. If you build the whole lot out of 4x4 posts and 6x2 tops, sawn and treated, you'll get change out of £200. Easily built in a day (if there aren't blocks of concrete where the holes must go).
Is that one you did? One of the reason I am hesitant about extra posts is the rear neighbours garden is about 50cm lower and there isn't a lot reinforcing/propping up the soil at the rear so it sometimes slips down and under the fence.
Those examples do look decent though.
Ahhhhhh rats. Makes sense but kinda hoped to avoid more post. Cheers for the reply!