house swapping

We're interested in doing a house swap on our next trip to California. Has anyone done this? I know there are several  house swap websites, but they are not free so we need to find one good one. If anyone has experiences to share or websites to recommend we'd be one step ahead.

We have not done house swapping but we've had housesitters in both our home in FL and in England. One of these days we'd like to try housesitting for others.
I do know people who arranged for a housesitter for their place (Scotland) and then turned around and housesat for someone else (San Francisco)
www.housecarers.com is the site we've had the most luck with.

Thanks, I hadn't thought of that option. We'll explore both. My mother is moving into a smaller place and it's just not easy for her to accomodate the five of us. Housesitting or houseswapping seems like an affordable solution.