I've been using a pair of Transcend 32GB 133X cards for over 18 months in a mixture of cameras including 50D, 1D3, 7D, 5D2 and never yet had a problem.
Mine came from 7dayshop and were £54 each when I bought them. The last time I looked the price had gone up quite a bit. If you don't need high write (or read) speeds then I think the Transcend cards offer very fair value for money.
I also have a 16GB Transcend SDHC card in my 1D3 and I filled that yesterday at Biggin Hill. Again, faultless performance from the card. I do have a Sandisk 8GB 30MB/s card, which was bundled with my 50D, but when buying cards individually I prefer the value offered by Transcend. If I needed speed over capacity then I'd get Sandisk.