Have you not seen the price of petrol? ;-)
I think it can work but it makes things harder. I've done it once, quite some time ago now, and only because he'd said he'd be willing to move here if it worked out (I own, he rented) but as time went by the reality of what that actually meant and the wrench of actually having to leave work, friends and family to move area and start again made it unviable, so I wouldn't recommend it. After a few months together alternate weekends, sometimes 3 weekends out of 4 and no prospect of seeing each other in the week just isn't enough to feel like it's going to work.