WP eStore comes with a lightweight lightbox solution. Most of our customers prefer the lightweight solution as it means better page load performance.
If the default lightbox option that comes with eStore doesn't work on your site then try this method.
1. Uncheck the "Enable Lightbox effect on Images" option from the settings menu of the eStore plugin. This will turn off the lightbox effect that comes with eStore.
2. Install and activate the "Lightbox 2" plugin from here:
http://wordpress.org/extend/plugins/lightbox-2/
Now refresh the page where you have the fancy product displays and it will automatically use the new lightbox effect on the images.
More advanced tweaks if you are a developer
Alternatively, you can install another plugin or a custom script that can show the images from your page using a different lightbox effect that you like. WP eStore adds the following "rel" attribute to all the thumbnail images that it outputs:
rel="lightbox[product name]"
So any custom plugin or script that can work based on rel="lightbox" should work.