No alert on that link, or browsing your store. So we would need information on the detection/s malware name or a screenshot image of the avast alert to see what is/was found.
A further update another avast forum member has checked this and got an alert but on orlandotrend.com not the ebay store side.
It isn’t your ebay store as such but the orlandotrend.com domain that is being alerted on.
When checking the ebay link you gave and your ebay store, using firefox 15 to with NoScript and RequestPolicy add-ons to check it out there are a hell of a lot of third party sites pulling in images and data. I selectively allowed them one at a time (including orlandotrend.com) so images and descriptions, etc. were displayed and no alerts.
However, now going directly to or trying to go directly to orlandotrend.com I do get an alert (image1, click to expand).
There is an on-line contact form, http://www.avast.com/contact-form.php?loadStyles for: * Sales inquiries; Technical issues; Website issues; Report false virus alert in file; Report false virus alert on website; Undetected Malware; Press (Media), issues.
If you are reporting an FP, then you get another input field open (image2), click Browse button and navigate to the file or enter the web URL for the site you wish to submit for review (Network Shield), etc. A link to this topic also wouldn’t hurt.