Yes, it is true. Very often the parts cost more than buying a whole new pump. It is the same situation with car parts as well. We use a 50% rule here. If the parts cost more than 50% of a new pump ... buy the new pump. A D30 can last a very long time. I have seen some in service for 25 years. The most common reason for the death of a D30 is either freezing with water inside or running it too long with mixed water/oil in the crank case and the crankshaft gets damaged and/or it seizes up. So keep a close eye on the oil sight glass, if the oil is milky gray stopping pumping immediately and change the diapragms.