If you haven't already - you may want to search the Gear subforum and also search the archives. I know a couple of guys in the past have discussed building their own fence, and they described the components at a high level, but I can't recall if they listed parts or vendors.
I built one last fall and it worked pretty good. Never had any bear encounters though imagine that. It was fun to drink beer and grab onto it.
I bought the Fi-shock unit by Havahart (~$60) from AK mill and feed in Anc. Lowes actually had the FI-shock poles for much cheaper than Mill and Feed in their gardening dept. They are white and have the built in clips. You can cut the pole shorter if you need more of a packable set up. I bought the 300 ft role of poly wire. So I came in about $115 for the whole setup.
450, Look on e-bay. I recommend the Zareba charger. It runs on four d-cells batteries and last for about two weeks. The post are the hardest part of the deal and you will most likely need to procure locally. Go with the 1/2" to 3/4" inch tape. It is easier to see for both us and the bears.
Here is a place to look at different options, Premier one supplies. I did not get my charger there but looking at the different setups help me design and plan my fence.
Due to shipping, I had to improvise with my poles. I used fiberglass fence poles and added premier one's clips to hold the fence tape.
One thing to make sure you get is a tester. It will let you know how your batteries are doing, if you have a good ground, and/or if you grounding out from something (normally grass laying on your fence). For the grass I carry a machete and give a little trim every few days.