Good question. First question is what kind of roof do you have? Wood? Metal? Composite? Second, is what is the condition of the roof?
If the roof is composite and in good repair, and if all you need is gutter cleaning and moss removal, I would think you just hire some general labor. The way I get moss off my roofs is to sprinkle moss killer all over it, wait for it to die and then gently brush it off or hose it off. Cleaning gutters is even easier. Just make sure you get them 100% clean so nothing sticks to the inside. You can also clean them and then repaint the inside if you see any rough spots in the paint. Also, make sure they're sloped properly. Finally, if you only have 4" downspouts, it's worth the money to upgrade to 5" or even 6" if your gutters can take it.