Check/refresh your eBay summary page to see if & which offer you received. T&Cs here and here. Good luck :)
$15/$20 off the purchase price on all eligible items listed on www.ebay.com.au (except exclusions listed) when you spend $100/$150 or more in one transaction. A maximum of one transactions applies. Multiple items may be purchased in one transaction (10 items maximum).
Excluded Items:
All items listed in the following categories: Cars, Bikes, Boats (9800), Coins (11116), Gift Cards (184609), Other Lots More Items (88433), Real Estate (10542), Services (316), Tickets, Travel (11730); and
All items sold by the following sellers:
(1) Officeworks;
(2) Fantastic Furniture; and
(3) Target.
maybe better than 10% if you can buy just 150 or 200. Still waiting for 15% off US or UK. Yet, not much to buy on eBay.