There is. You can replace our standard search with your own by modifying the admin UI. It would be pretty trivial to do the search and further filter the results before returning them to the user.

Extending uCommerce Admin will tell you what you need to know about extending/modifying the UI.

You can perform a search by using the class ProductSearchQuery and setting the appropriate fields on that.

To execute the search you go

var products = ObjectFactory.Instance.Resolve<IRepository<Product>>().Select(new ProductSearchQuery()));
// Filter out variants from seach result
products.Where(x => x.ParentProductId == null).ToList(); 

Hope this helps.