How to carry four bikes on a car and not pay out a fortune?

I love cycling and regularly do rides of 50 miles or more. My wife is now getting into it as well, to the point where we’re doing the 100-mile RideLondon Olympic legacy event on 4 August. This year we’ve also encouraged our children into cycling – as a way of getting out as a family and keeping fit – and yesterday we did a couple of hours off-road in Thetford Forest. Next we’re all doing a 16-mile charity ride. It’s obviously not far, but my daughter is only seven. The issue we’re now having is carrying four bikes on a car. Hatchback-mounted and roof-mounted ones are great for up to three, but the only option for four is a tow-bar mounted carrier. So I hit the internet last night and got a bit of shock. The cheapest one I could find was Halfords own at £260, though it’s down to £179 at the moment. Lots of reviews saying it’s good for the price, but suggesting it’s heavy and lacks security. Top end one is Thule at nearly £500. Not cheap but it will probably last forever. My experiences with its products in the past have been nothing but excellent. Other issue is as the moment I don’t have a tow-bar fitted so that’s going to be more money.