Debra's fix for this was similar, but she also added a variable to set the default value the same way as the product's minimum:
<input type="text" name=amount size="4" value="{$product.min_amount}">
Here:
http://forum.x-cart.com/showpost.php?p=109039&postcount=7
The problem I'm having (if you haven't noticed from some related posts -- please excuse the possible duplication), is with multiple ('wholesale') pricing levels. Am not sure how to execute this js function with a text box when it replaces the drop-down --- the javascript is supposed to update the price immediately based on the quantity being 'moused over', (er, mouseovered?).