sorry, I should have been more specific.
I use an extract in capsule form: Goji Berry Extract 500mg (4:1) equivalent to 2000mg. So a double dose is 100mg (4000mg equiv.)
Or take double dose for a week if leaving this for special occasions (dirty weekend away!) if you dont take it everyday.
I take it daily, and have second a couple of hours before 'time' as I personally believe it builds up more than a one dose pill like viagra, but this is natural and has lots of health benefits, so why not take it everyday
The best in the uk is easy to find on google, 7.99 for 120