Is "high end" hyphenated, or not?

I would.

If it is used as an adjective (e.g., high-end products), yes.

According to the Associated Press stylebook — here, let me Google that for you — “Use a hyphen for compound adjectives before the noun: well-known actor, full-time job, 20-year sentence”.

Yes using the hyphen is the preferred form. As in high-end audio

@bob_ is correct.

If you leave the hyphen out and get an odd sounding phrase, replace the hyphen.

High end products can be read as Tall “end products,” whatever they might mean.

Y-S

Yes, high-end should be hypenated….