BasicSeller creates a new button in the Merchant window that lets you sell all your gray items with a single click.
It has a tooltip that shows the total sell price.
If you don't use guild repair the button is places next to the single item repair button.
If you use guild repair then the single item repair button has been removed (who uses that button anyway?) and replaced with the BasicSeller's button.
Check the screenshots.
1.1 Updated for 5.3
1.0 Initial Release