This tutorial shows how the main data is calculated when you list a grouped product.
Before listing grouped product read eBay multi variations requirements.
A variation lists and appears on eBay only if its product Status is Enabled and Stock Availability is In Stock
#54 Grouped Product, that has #51, #52, #53 associated products:
This product in Listing:
eBay Available QTY is the sum of quantities of all associated products:
54+170+142 = 366;
"Buy It Now" price is the min price of associated product that can be bought on eBay: $129.99.
eBay only displays 30 characters of the 55 characters allowed in the drop down field for Multiple-Variation listings. Click here to find out how to set appropriate Title for Variations of the Multi-Variation Item.