Some quick prefatory comments, friends. I understand that this is a general question; that for a successful hedge fund manager, tour-guide pricing is not an issue; and that for those with very limited time in a place with much to see (a cruise excursion), a wise investment is a really tour guide.
But for those not actively involved with hedge funds but also not booking nights in hostels, and with several days in a location, I would welcome opinions on when, regarding price point per person, you think a private guide is cost-effective or a good idea, and is not a good idea.
Because the question is general, I opted to post on this forum. But in my particular case, I will shortly be visiting Berlin as a solo traveler. For a group of four or six, it is very cost-effective to hire a private guide. But for a personal tour, the pricing can be steep. And I do intend to take advantage of group tours before any private tour.