Tandem bike tag along - $80 (Rustburg)
Great for young beginners to learn pedaling and balance. Allows parents to control the child's location at all times, keeping them close and out of traffic. My son and I had loads of fun with this on the Blackwater Creek trail, but he's outgrown it. Comes with everything you need to mount to an adult bike. Priced $20/30 cheaper than a new one and you can avoid shipping costs.