I pay £20 for 3.5g, £40 for 7.5g etc etc. One of my suppliers, Jon, gives fucking good deals (I'm one of his bird's best mates) but sadly he only sells in eighths and quarters. Persuaded him to sell me an ounce though on the 12th December, charged me £160 (only supplier I could get hold of, the others were out of town or dry )but when I got back and weighed it there was 40g in there!!! So, being the kind soul that I am, I sold my other mate Ben an eighth for £20. Only it was a Q instead.
Treat your friends good, and they'll do the same back.