Well it would all depend on what ones budget might be. And as Docrwm mentioned it would also depend if one would really need and/or want a flash versus something such as continious lighting.
For continious lighting I've stumbled upon something a bit out of the ordinary that works perfectly. Snap-On (which is NOT known for budget conscious people) has a type of angled light - the Snap-On
CTFL918. The iterm number, and the
F portion of the model number, and even just looking at the item - all show that it is a florescent item -and that perhaps the camera setting might need to be adjusted to compensate. But for some strange reason - all of mt non medium format cameras seem to adjust to it - perfectly - almost as if it were a daylight source.
But that Snap-On product as noted earlier is not inexpensive and also needs their version of a dedicated battery. But I've also had one for many years and it works on both hobby use and also even professionally. With a proper type of clamp one can position it about anywhere.
Also...
Lomography 4-Color Ringflash 405 B&H Photo Video
Even though this is clearly labeled for lomography; I've used this on a variety of cameras and then switched over to B&W with some stunning results.
Dot Line 48 LED Ringlight with AC Adapter DL-RL48 B&H Photo
This one has far above average results for the price - also quite adaptable for most lens'/
It's also unfortunate that the Pentax version typically goes for over 450. But I've seen some out there that go for well over three times that.