Where to buy a DDR3 MXM 3.0A graphic card?

[Glitchy]

Where can I buy a DDR3 MXM 3.0A graphic card from a web vendor? Web searches only bring up ebay and not the cards 'm looking for.

The machine came with a NVIDIA GT425M 2 GB, but I am ok with a ATI Radeon HD 6550A or NVIDIA GT425M 1GB or 2GB.

I got a new HP Touchsmart and the video card is bad. If HP wants me to send it in, wait a month and then have to take a day off work to sign for delivery, I'd rather just buy one myself. Thought I should make up my mind about replacing it myself before I call HP and request a replacement.

Thanks

Jeff