I have not had experience with Dayco, so, cannot offer an opinion on their quality.

My idler pulley was notchy, corroded, and looked like hell, so, that was an easy decision. The tensioner was much the same, so, that one got the toss.

My tensioner spring was 6 mm past maximum specification, so, I went to the dealer for a $5 spring, just to be sure.

The water pump, had to be replaced while I was in there, could not get up in the morning and look at myself in the mirror if I did not.

Yup, $125 bones is a bit of money. You will have to make the call on what you are comfortable with. I would play around with the pulley's a bit, preload them sideways, turn them very slow, feel for any "rumbling", notchy type feedback from the bearings. Any sign of that, out they go. Mine had at least 60k miles on them, so, easy decision to discard.

Mike