Limit and Home Switch Choice

[EddyCurrent]

Agree with Jazz, have separate home and limit switches, also as he says home switches are inside limits. In reality your machine should never hit the limits, you should use the soft limits in Mach too.
PMDX sounds good from the descriptions above, you need to keep the limits in hardware only.
I'm going for one limit per axis with adjustable strikers at each end.
Home switches need to have good repeatability so that's the parameter I think is most important, at the moment I have not decided myself which ones to use. If you decide on proximity type remember Mach strikes the limit then reverses slightly so potentially it could crash into the switch if homing speed is too high, this implies you mount them sideways but this might affect the detection repeatability.
You mention buying cheap switches but it's like cheap tyres, I'd want them to be reliable otherwise machine can be damaged at much higher cost.

[JAZZCNC]

If you decide on proximity type remember Mach strikes the limit then reverses slightly so potentially it could crash into the switch if homing speed is too high, this implies you mount them sideways but this might affect the detection repeatability.

You shouldn't mount the switches so they get rid upto but rather get rid over then this doesn't happen, This applies to the limits has well.
With Proximity switches then generally the closer you set the gap the better or sooner they detect. With the threaded type you can use this to fine tune them.!!