If you're looking online, I recommend Sohfast, Import Auto Salvage, or hmotors. I personally ordered from Import Auto Salvage and I would definitely order from them in the future. The swap came with everything I needed, which was great since there wasn't a lot of down time waiting for parts. It was expensive, but well worth it.

It will be difficult (and time consuming) to do the whole swap on your own. I did most of mine, but it was necessary to have another person help with working the new engine in. In terms of skill level, all you need are the right tools (see other threads). If you can change a suspension and solder wires on a stereo, an engine swap will be not be anything new. It just takes longer.