I think the only Keysight below $700 is the DSOX1102A. 70MHz, 2 channel, 1Mpts, 2GSa/S, 50k Wfms/s (not including hacks)
It's actually a 2+1 channel MSO, but who's counting...? ![Popcorn :popcorn:](https://www.eevblog.com/forum/Smileys/default/EatingPopcorn.jpg)
That is the sort of thing that I would expect, after a few years of hibernation with a TDS210 and a TEK2445, that all modern 2 ch scopes would do.
EDIT: It's a digital world, and in a scope with decode options, a 3rd input is obviously handy, and should not be that demanding to implement. Or so I think...