I have the wetokoles as well. I've had mine for over 3 years and they are the best seat covers ever. I have gotten oil, mud, etc on my seat covers and after 20 minutes with their cleaner they look brand new again.
I know $300 is a lot for seat covers, but in my old truck normal (cheap) covers cost about $40 and would last 6 months or so before they looked terrible and needed to be replaced. So if you plan on keeping your truck for a while - they are definately worth it.