I was just reading an advertisement for the K&N brand oil filters. Does anyone have any experience with them? Are they worth the extra cost?

You'll get oil filtration that's good as gold with these K&N oil filters.
Keep your engine free from contaminants as small as 10 microns with these Performance Gold K&N oil filters. They use a resin-impregnated filter media to provide maximum filtering, and an inner core to lend extra structural support to the filter, preventing filter collapse. Plus, these K&N oil filters have an anti-drainback valve that eliminates dry starts and prevents oil from draining back into the crankcase during engine shutdown. And they're protected by a heavy-duty outer shell that guards against rock and stone damage and provides over 550 psi hydrostatic burst strength. So, if you want golden-level oil protection, then you want K&N oil filters. By the way, I don't work for K&N.