Thinking of buying/building machine for PCB milling

[Jonathan]

I am looking to buy a 3-axis CNC router with the main purpose of milling PCBs but also more general purpose - small wood, plastic, foam, thin aluminium control panels.

Looking at all the Chinese 3020 / 3040 routers on ebay

The machines you refer to would be acceptable for everything you listed, except maybe the aluminium, so long as they come with ballscrews. You need ballscrews to get the required accuracy for engraving PCBs. I'd be very concerned if you're planning on using one of those machines to cut aluminium regularly, or are expecting it to do it accurately and quickly.

Marchant Dice Ltd. / Worldofcnc.com was looking promising.