Anything that can do intensity grading and long persistence can do color grading with a modest software change in the graphics code, but yes, I think Siglent scopes are cheap end ones that have bothered to implement it. LeCroy scopes have had it since they went to color screens, so you may be able to find an LC series scope that was cheaper.
It's certainly an interesting feature, and I find it easier to glean data from than a regular intensity graded persisting screen, but it's really barely even a feature, basic implementations would only be a few lines of code, though it could be more with controls of it or with certain methods of drawing the display.