The Solar Spirehawk is dropped by Rukhmar, the world boss of Spires of Arak. The mount is not eligible for bonus rolls, but must be directly looted from the corpse. It can also be listed on the Black Market Auction House.
Here you can buy Solar Spirehawk for EU or US Servers.
You'll get guide for getting Solar Spirehawk
You'll be able to get Solar Spirehawk
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