I understand the mentality -- I mean, a good cello can cost more than a house -- but as a musical tool, it also has to justify its existence to some extent. If you're playing Mustang Sally in a local dive bar, you might want to think twice about taking it out of the house, since any pocket money you take home from the gig will be immediately eaten up by depreciation. On the other hand, if you're opening for guys like Pat Metheny or playing in a late night show's house band, you're probably commanding enough of a salary that it'll pay for itself in a couple of years.