Thanks for the tip! The wheels on my creeper are pretty rough from 8 years of having an old asphalt driveway. Now I'm on concrete again and looking forward to getting a creeper with smooth wheels.
On the subject of NAPA sales: they have a filter sale every year in the spring, late March or early April. It's about a week long if I recall and offers a pretty deep discount, but I haven't seen it heavily advertised in the past. Apparently one has to call and ask or drive by and notice the signs outside. I was just in there yesterday and heard it mentioned the sale hasn't happened yet, so keep an eye out for it to happen in the next few weeks.