Apprenticing is basically a dead art. If you want to learn, you have to pay, or go the DIY option. Or Both.

The reason nobody is into apprenticeships, is basically because as an apprentice, you milk the 'master' for his knowledge, then bugger off and open your own shop, ending up in direct competition with the 'master'. You're no good to the 'master' for a long period of time as he/she teaches you the basics, so by the end of the entire experience, most 'masters' don't feel as though they don't get enough out of the deal.

It's an understandable position.

If you want to learn, your best bet is courses - bike specific or just brazing/welding/fabrication - or DIY using whatever resources you can track down.