Hm, that page didn't have any of our buttons when I looked. At any rate, our standard button codes don't impose any particular spacing, so that is probably coming from your own site's CSS or other layout code.
The top of this help page explains how to modify your E-junkie button code to replace the standard button image with a custom button or text link:
http://www.e-junkie.com/ej/help.custom.purchase-buttons.htm