Looking at tow bar mounted bike racks
That's an expensive way to carry bikes! You can buy a suitable tow-bar for about £250, BUT then you've got the cost of fitting ..... ~£150-£200, if you're lucky! You might not get much change out of £500! I take two Raleigh Evo 7 folding bike's abroad with me on a regular basis. There's still plenty of room in the rear! Holland is just wonderful for biking, too!
David