I don't think any of the retail models out now will feel anything like the Makos. With that said, you do have one piece boot options in the Jetspeed FT1, CCM Supertacks and Verbero Vortex and Cypress models. If you're thinking of spending the coin on top of the line retail models at full pop though; I'd seriously consider the VH/True route.
What size Mako would your son need? I search for Makos in my size periodically and come across others - I could let you know if I see your son's size.