Don't use solder paste actually, I've always found it to be more trouble than it's worth. I just use fine flux cored solder. When building for my own purposes, PROPER solder as well, not that lead free crap

It's fairly easy once you've got a steady hand, a good soldering iron, and twenty years experience Lots of flux is essential though. I go through a lot of flux pens.

As far as the costs go, it's going to depend on quantity. One off, the component cost is in the hundred and fifty pound region, but that's subject to massive revision downwards once the quantities go up. The PCB is the least of it really - the boards cost about £18 each 10 off from a chinese manufacturer which is pretty good for a good quality 8 layer board 120mmx100mm in small quantities. The price drops like a stone when the quantities go up as well.

There's a lot more to the cost than the actual cost as well of course, but I'm certainly planning on selling the things if possible. I have a customer for them already, for embedding into a completely unrelated and non-obvious (and fairly expensive) project, and hopefully this will get the quantities up to the point where the cost is reasonable.

So far I've managed to test everything except the ethernet, which is going to take some effort. First, I need to persuade the horrible cirrus linux distribution to actually compile...

pca