The champion spawn artifacts that came out a couple months ago are a lot more rare yet have less durability (150). I think that faction artifacts should be more disposable so that you aren't set forever when getting one. Perhaps 100 durability would be better. The most expensive items only cost 5,000 silver which is not at all difficult to get. Also if you can use powder of fortification on them it should be disallowed. So a faction artifact will last ~3 months with casual play (repair every 2-3 days). Or it will last about a month with heavy usage (repair 1-2 times per day).