I only get them from the garden centre when they are rock bottom price, I have got some from ebay and have had good success, but watch out for postage charges, can be dearer than garden centres. My daughter has a Works shop where she lives in St Austell, they have them for 25p per packet.
I have scrounged loads from my daughter, and collected from my own plants, and now Amateur Garden mag has started free seeds right through the year, so have lots there as well.
(I know what you mean about the i pad!!!)