Hello Mr. Macintosh - and welcome to the world of Newton. Styluses are very cheap - I've seen them as low as $1 a piece on eBay, so definitely go that route. The battery packs (and chargers - did you get one of those?) are rare, but there's a guy in Germany (www.pda-soft.de) that does them, I think.
As for the flash card, that might just be dead. I know mine went out soon after I got my 110 about a year ago. They have little batteries in them, and once those go, it's gone. But flash cards you can grab from eBay, too, and diagnostic software can be picked up at www.unna.org - along wit