You really need to look at the actual house and houses that are near by. the house could be advertised at 300k but might only be worth 200k in the current market, but then again it might be worth 295k (but i doubt it)
If you think 260k is a fair price and your happy to pay it, then that ok. But if your pushing your finaces for 260k, then i'd maybe hold off for a few months more. Dont worry about an offer being too low, the worst that will happen is its refused and the best senario is €€€k saved
If you think the house would have been sold if 2006/7 for 300k, i'd definatly wouldn't offer more than 230K, but thats irrlevent with out knowing the house.