The AC Adapter costs only $3.50 for a brand new one for the Atari from
MPJA. The stock number is 12254-PD
You can also find other actual Atari adapters from various places online. If you are interested look at
My Bookmarks look thru my Games & Accessories section.
For the RF switch are you simply refering to the TV/Computer switch that the cable from the Atari hooks-up to? If so these can be bought new from Radio Shack for $7 each. Or if you have a Cable-Ready TV you can get a connecter for about $2. It is a RCA to Cable adapter. I don't know much about that, except many people swear by it. My local Radio Shacks don't have it.
Of course you can use a TV/Computer switch box from another Atari, there is nothing special about them.