The Reins of the White Polar Bear is an item that can be used to summon a polar bear mount. The reins can very rarely be found inside Hyldnir Spoils. The estimated drop rate is ~1%. It can also be listed on the Black Market Auction House.
Here you can buy White Polar Bear for EU or US Servers.
You'll get guide for getting White Polar Bear
You'll be able to get White Polar Bear
Additional budget for Character transfer or Character boost to max level. BMAH Services in Shadowlands now requirement to have a max level character on server, so Trial character will not work.
Free time on evening, if you choose selfplay option