When I did my lathe & mill about a year ago (6 scales) I engaged Ditron via their chat on Aliex and the pricing was significantly different from their Aliex page. They threw in 1u resolution N/C and the linear (glass scales) were a fair bit lower in price compared to the magnetic. If you hesitate for a day or 3, you might get a better offer or something thrown in too. That's how I got the 1u for free. If I recall I was close to month end too.
For buying a mag read head it was less costly to buy a short mag scale than just the head.
I'm quite happy with my glass sales so far and the tape mag scales I put on my mill quill and embedded in my lathe cross slide have performed well too. The tape is great for confined spaces but I'm more trusting of the durability/reliability of the glass type.
I'm interested in the latest market info because I'll need to be fitting up my newly acquired SM 1120.
D