Securing New Residential Fridge Doors/Power Needs

When looking at an ivertor what all should you look at or look for? I see them on E-Bay all prices. I also think I know you get what you pay for. All I plan on using it for is the Frig while on the road, the frig will be already cold, and most of ours trips will be 4 hrs or less and the TV should be keeping the batterys charged while driving.
Thanks for any info.