I did exactly the same trying to get hold of a Nintendo DS. Went round all the shops in Taunton & Exeter, phoned every retailer, went up to Toys R Us in Bristol - all to no avail. I was getting to the point that I would have mugged a small child to get hold of one! In the end I had to approach my daughter and ask her if if she would want something different, or wait until after Christmas. Bless her heart, she said she'd wait.
Little does she know that I managed to get the last one in Bromley (SE London) when I dragged myself in there with a huge hangover after visiting friends. Can't wait to see her face!