The IBM Proprinter was a dot-matrix printer.
Here's a nice IBM video ad for it from 1985. Note the presence of the 5170.
There was a real push in the 80's to get dot-matrix quality up to NLQ. Sanders made multi-pass printers with downloadable fonts that could mask a lot of the "graininess" of a dot-matrix font. The Japanese, having a need to print Kanji, with its fine detail, pioneered 22-wire printheads.
Daisywheels aren't bad if you're doing insurance forms or office correspondence, but when you need to change fonts, they're a pain.
In my experience, it's almost impossible to give away a vintage daisywheel printer, regardless of condition today.
Addendum After thinking a bit, I realized that the IBM Displaywriter used either a selectric-type (5215) or a daisywheel (5218 ) printer. These were circa 1980, so they preceded the 5150 by a couple of years. You could also see these things set up with IBM mainframes as printers for logging (i.e. low speed) and such.
I don't think the 5218 was ever marketed for the PC crowd--it wasn't a "dumb" printer by any means. The DW was an EBCDIC machine and the printer codes were quite a bit more involved than the usual MX-80 stuff.