In SR5, the Professional Rating 6 lieutenant has an F6 qi focus and an F2 weapon focus.
Going back to previous editions, there are some foci in Street Legends and Street Legends Supplemental from 4E that might offer some guidelines. 4E is thematically similar enough to 5E for the comparisons to be relevant. (Foci actually cost less in 5E in terms of both nuyen and karma binding, and their Availability is a bit lower too.)
For example, lots of the legends have foci in the F2 to F4 range.
At the high end of the scale, Lugh Surehand is running around with a bunch of F10 foci, plus a surprisingly modest F4 power focus.
Harlequin has a bunch of F5 to F10 foci, plus an F16 weapon focus.
To gently counter some of the previous arguments being made, I wouldn't advise using nuyen costs as a good guideline. The ¥128K you put into Wired Reflexes 2 (very reasonable) would be able to buy an F7 power focus or an F18 weapon focus or an F42 qi focus (all ridiculous). Instead, I would advise using Availability as a better guide as to what's appropriate. Availability 12 - same as Wired II - get you F3 power and weapon foci. Availability 24 - the limit of the Restricted Gear quality - gets you F6 power and weapon foci, which are serious business.
I might broadly group foci this way, acknowledging in advance that an F4 qi focus is very different than an F4 power focus. These categories are more for the latter:
F1 - F3: regular runners
F4 - F6: prime runners
F7 - F9: superior/superhuman runners
F10+: legends only
