For non-optical remote shooting, any Nikon Speedlight from SB-80DX onward is perfectly serviceable. Older Speedlights may work, as well, but I settled upon SB-80DX as the oldest I would actually purchase, when I did my comparison of specs several years ago. These can sometimes be found at very friendly prices. I bought five or six of them, only to experience a flood claim all but one of them, before I added radio triggers.
For ease of use the Metz 64 AF-1 is a new favorite. I realize it is beyond the OP’s stated budget, but forum topics are useful to all, not just the OP, and, some lesser Metz flashguns have similar features. The wonderful, highly-visible touch-screen menu is so very user-friendly, and, at least when on-camera, the menu rotates when the camera is rotated to vertical orientation.
I do not hate the other third-party brands. Metz and Nissin are what I have experience using, and I like Metz better.
+1
NOTE: Nikon SB-80DX does not use the newer iTTL mode that most of the Nikon dSLR cameras use.
This note is for anyone else reading this thread and considering a flash unit for their Nikon dSLR camera.
The Nikon SB-80DX does not have the newer iTTL that is used in most of the Nikon dSLR cameras.
It uses the older TTL from the film days.
So, if you use it with a Nikon dSLR that only supports (iTTL), you won't be able to use it in TTL mode.
Instead you'd either have to set it manually or on the non-TTL auto mode (Thyristor auto mode.)
Take care & Happy Shooting!
That is why I said “for non-optical remote shooting.”

The OP specified this, and stated he was already using one non-CLS/I-TTL flash.
+1
Absolutely.
I'm just thinking if anyone else reads through the thread and adds the Nikon SB-80DX to their short list not realizing it doesn't support iTTL.
IMHO . . . if someone is only going to get one flash unit, or this is their first in the series . . . then having one that does TTL with your camera is nice to have.
Actually, the SB-80DX does work with a digital-era TTL mode, known as D-TTL, which was in the D1-series and D100, and cameras as recent as the D2-series may be able to use the SB-80DX for TTL shooting.
+1
I had the Nikon D100 and Nikon D70s. D100 was the D-TTL and the D70s was the iTTL.
That's why I knew of the switch.
None of my flashes back then had either D-TTL or iTTL! LOL.
Vivitar 285HV flash units were auto-thyistor AUTO mode or manual mode, that's it.
I had a Pentax AF540fgz which had P-TTL with the Pentax dSLR bodies, but when I wanted to use it on my Nikon cameras, I had to put it into auto-thyrister AUTO mode! LOL.
But when I started getting Nikon flashes, I aimed to concentrate on iTTL flashes.
I guess, now that I have a Nikon SB-800, if I want to use that flash on my Pentax dSLR, I can toss the Nikon SB-800 into auto-thyrister AUTO mode and I can get rid of my Pentax AF540fgz flash.
It is quite true, however, that the SB-80DX is not capable of CLS/I-TTL shooting.
I'm just wondering . . . I was planning to add Yongnuo YN622N-II wireless iTTL triggers to my Nikon SB-800 flash units. It's supposed to give me full CLS control to the SB-800 flash units.
Thinking about it, getting a Nikon SB-80DX, would mean not being able to do that radio wiressless trigger then.
So, if planning to add wireless radio triggers and wanting to control the flash units remotely, then it might be easier to stick with iTTL?
Take care & Happy Shooting!
