What would help you immensely, the $100 or the Roboduino? And what's an "etching plan"?
If you're short on money just buy the ready made and tested Roboduino. If you want to do it all yourself (including etching) you'll end up paying more for sure! I'm considering building an Roboduino myself (because I want to support it with my SoR Scope toy), but here are my reasons. Compare my reasoning to yours:
- I need an Roboduino because I want it supported in my SoR Scope program
- I don't want to buy an Roboduino: I'd end up having no fun at all with it, I'm sure I'd have no problem programming it and it would be too easy. Building it would be fun because it would give me a challenge. Programming it would be less interesting since I've allready got an number of other Atmega's programmed, including the Axon, the $50 and my Atmega324-based "$50".
- I have an hardware (ISP) programmer so I don't need an pre-programmed Atmega for the Roboduino.
- I have most of the parts, including the Atmega168, crystal, capacitors, resistors - I just need to buy the USB-to-TTL converter chip.
- I've only soldered SMD parts for fun and testing, never actually got them to work in a real project. The USB-to-TTL converter is SMD, so I'll have fun with that. And yes, I'll order 5 chips to start with, just in case I'll ruin the chip while soldering.
- I've etched my own boards before.
- I've just bought some double-sided blank pcb's and I want to test them with something, anything! I've only done single-sided PCB's so far.
- I've got some Press-n-Peel Blue transfer film and I want to play with it.
- I bought the vertical stand for my Dremel and a small caller to hold by PCB drilling bit and I haven't got the chance to test them.
Really, it's an paradox, but it's true. Building it yourself really is going to cost your more - unless you allready have most of the prerequisites. If you absolutely want to build something yourself build the $50 board: that board is designed to be made onto a perf-board (so no etching), uses common parts (you'll find them in Australia no problem) and there's a lot of support for building that on the forums.