This one really depends one what you FEEL like doing. To rebuild a power supply the way it should be done can cost you about 75% the cost of a new one.

Sometimes, I enjoy the feeling of doing it myself, especially if I have all the parts lying around ~ bridge rectifiers, heat sinks, fuse holders, fuses, pins, diodes, etc. But if I'm low on parts, I have no problem parting with $60 ( or whatever ) for a repro. It is the muscle behind the whole operation afterall, and its money well spent to have a reliable and stable power supply.