Although my CNC build is not completed yet, I'm a little concerned about poor accuracy caused by "lost steps". Stepper motors are obviously the most "cost effective" way for DIY CNC, but I wonder if these can be vastly improved with a "cost effective" encoder system? I've seen the hybrid stepper motors with built-in encoders but they're not cheap. I guess THESE add-on encoders are decent value at £30 each, but I can't help thinking that it can be done for less.

Has anyone here experimented with DIY encoders? Maybe something like this? Rotary magnetic encoder modules