Yep, You can find SPD as a substat on all artifact gear, with the exception of Boots that have SPD as a main stat. In Addition, you can find additional SPD substats on your Banners, but not rings or amulets.
Speed tuning is deathly crucial for team optimization, and at the very least, having your champion's speeds curtailling your other champ's so that debuffs like DEF DOWN land before AoE attacks or INC ATK before AoE attacks.... obviously you probably know this by 60+ days in.
200+speed as a benchmark for all your champions may prove to be quite challenging for having just played 60 some odd days.. you will need 6 star fully ascended champs in order to see the highest base stats for them, and like I said Banners can offer more speed as well. This is not to say that you CANNOT reach 200 SPD without these things, however.
Id say if youve got your CB team down and are getting your highest chest, and can clear dragon 13 at the minimum you can start farming for speed gear. Some of my Champion's have 2 or even 3 full speed sets of gear on them, many of those pieces with double and triple rolls of SPD, and many of them without any SPD in the substats. Why? Because this is the easiest way to build speed for me, 12% to 24% to 36%, the latter almost giving as much SPD as a 5 star Speed boot artifact.
I consider myself to be in mid - to - midlate game, and 200 Speed as a threshold for my builds is very much attainable with a few of my champs hanging around 240-270 SPD. Even is the case for my tanks/HIGH RES/ and revivers.