Nissan Maxima Ignition Coils going bad?

Hooked up my code scanner yesterday, and there are no pending codes.

The mileage seems to be down slightly, but it’s hard to tell. I normally expect to go 320 miles on 16 gallons, and it needs a refill now at 300 miles. If it went from 20 to 19, I just can’t say the mileage is suffering – too small a sample size, and 20 to 19 doesn’t really represent anything.

I’m at a loss. I haven’t run the manual’s test (just an ohm-meter) yet, but that’s next.

If I do decide to replace the coils, I’ve found out that the local store wants $135 for each coil, the dealer wants $100 each, and that I can get them on rockauto for $35-$50 each, or I have my pick of sets from eBay for under $200 (some way under $200). If it’s only $200, I’m not going to stress – this really is a 30 minute job to change all 6, and it’s hardly like buying a house. But I’d like to know the experience people have had with this variety of options. If the $170 option at eBay has been working for people – why not try it?