Hi,
It's a good domain. It's phonetically pronounceable (well, apart from Harper) and appears to have meaning in other languages. Harpa = Harp?
Either way, I like it and it's taken in many other extensions and has a good amount of Google returns. It's aged, which is a selling point as it may help with SERPS.
I'm not an expert in assessing the values of 5 L .com names since I only recently started to acquire them myself. That said, this is one of the better ones IMO for the reasons stated.
I would market this name to possible endusers if it isn't TM'ed. Unfortunately, none of the other extensions I checked appear to be developed.
I would expect at least $xxx from a reseller for this name.
Matt.