It never ceases to amaze me how reasonable these are priced for 8Gb these days and you cannot go wrong with SanDisk, particularly with their 5 year limited warranty.
Still for more details you can read the notes below or to buy SanDisk 8GB 
Technical Details
* Memory Capacity: 8GB
* Speed performance rating: Class 2 (based on SD 2.00 Specification)
* Supports SDHC compatible host devices
* Non-volatile solid-state
* data will be lost if device is switched off before device has finished writing to the card
* Low battery consumption to maximize battery life in small portable devices
* User selectable mechanical write protect switch on the exterior card casing
* Operating shock rating of 2,000Gs, equivalent to a 10-foot drop to the floor
* Security level complies with both current and future Secure Digital Music Initiative (SDMI) portable device requirements
Features:
* High transfer rate for fast copying and downloading
* Large storage capacity, up to 8GB
* Built to last, with an operating shock rating of 2000Gs, equivalent to a ten-foot drop**
* 5-year limited warranty
**Based on SanDisk internal testing
Note: 1 megabyte (MB) = 1 million bytes; 1 gigabyte (GB) = 1 billion bytes. Some of the listed capacity is used for formatting and other functions, and thus is not available for data storage.