I've seen those wedges in one of the baby catologues, NCT? Bolloming marvellous? Jojo maman?
We've used a pillow and a v cushion before, DD actually slept on the v cushion for 4 months, totally against everything you are told about cot death etc, but it was the best thing for her.
I've seen other people put telephone directories or coffee mugs under one end of the bed!