SG4 Skycaddie has broken screen - is cost effective to repair?

Generally no. The way replacement parts are priced you
won't be too far behind what a new one is. Having said that I just checked prices and you are paying a premium price for it so it might be worth it. A replacement screen IF you can find it should cost about $100 plus labor and shipping. Here the trick, you may not have warrenty but check for it. And see if they offer repair/replacment services. Most GPS manufacturers will repair or replace the unit for a nominal fee right around $100. You either get a refurbished unit or a new one back. The nice thing is that they are not too picky sometimes on whats wrong. So if you ran it over with the truck and then dropped it in the microwave they usually don't care. Do that with a laptop and they scream user abuse and tell you not very nicely to go away and not bother them.

For what it's worth, I dropped my SG5 on to a cement surface. It appeared undamaged, but the satellite receiver was apparently affected and it would no longer receive satellites. I sent it back through the retailer (GolfTown) and SkyCaddie replaced it free of charge even though it was out of warranty. It took two months, but the price was right!