Lifter noise - when is it time to do something?

[Dave Haupt]

1989 200 TQ Sedan, 10V, 145k miles or so....

It's been making lifter noise for quite a while.  The
longer it's gone without being started, the longer it
makes lifter noise.  Tonight, having not been driven
for about two weeks, it made noise for two miles, then
the car was stopped for bathing, then two miles home -
lifter noise the whole time.

Would I be doing damage if I continued to ignore it?
And, if I choose to do something about it, must I
replace all ten, or is there a way to
deterministically know which "one" to change?  And,
from the BTDT department, how much time does this
take?  How much should a mechanic charge?  Do I need
to deal with it?

TIA!

Dave
Santa Rosa, CA

1989 200TQ 10V Sedan, Lago Blue, $1.20 per mile and
counting
1991 RX-7, modified, failed transmission, selling as
parts car
1988 Trek 8500 aluminum, Deore XT, daily driver

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