Buying it for resale is very tricky. You can get a chip taken off if you have access to a glass repair person. The person I go to in Vancouver, charges $30 an hour, minimum one hour. Even then not all chips can be repaired while retaining the look of the original piece. And certainly not every city in North America has a glass repairer who could do Murano quality repairs. Another factor is that these Picasso faces are now mass produced, both in Murano and, I suspect, China, so you have to be very sure you have one by a respected maker in order to have any chance of getting your money back.
If your buying to keep, I agree with the others that often the only way I can afford a very good piece is if it's slightly damaged.