show me the money
Didn't expect to see one of my Reddit comments appear in a WoWHead article.
Fastest way to a speed set is to buy the items with Tertiary Speed stat from the AH. They won't get you the full 275% speed, but, when enchanted you can still get a decent boost. Unfortunately the S4 drops were made BoP (and sometimes drop with the tertiary stat, but rarely), so the only ones available are left-over S2/S3 BoE ones with a lower item level, and can no longer be upgraded, with a max. level of i424. Depending on your server, these were selling at between 25-150k a piece. Bear in mind you don't want to spend a fortune on the Head/Shoulders/Chest item as you'll replace these with the Azerite Longstrider piece.You will still need to follow the advice to get the Heart of Azeroth, Longstrider, the head/shoulder/chest BfA pieces, & Onyx Amulet as soon as you can. Mortia has a decent Speed set guide with more details on obtaining the pieces for other specs, talent points etc. One important point they note is that the best Azerite pieces actually come from Normal dungeons (max. i181 v i157 heroic and i159 mythic). Either Blizzard developers got something wrong in the stat squish or deliberately allowed them to be farmable. Worth reading the comments too, as there are links to other sources and tips such as maximising Haste (irrespective or not of it being your "best" stat or not) to take advantage of Drums/Hero/Lust +Haste buffing Longstrider.