You choose a "free" gift when you sign up to eBay Plus via the link, over 1600 items to choose from, some of them with normal price over $49.
You can search for eligble items on the linked page.
Example items Mario & Sonic Switch(ebay.com.au)
Super Mario Odyssey Switch(ebay.com.au)
Catan Legend of the Conquerers Expansion Board Game(ebay.com.au)
Dualshock 4 Controller(ebay.com.au)
New Super Mario Bros U Deluxe Switch(ebay.com.au)
The $50 voucher is hard enough to use, if they replace it with this i wont be resubbing