Is there a way to list all items at the store? it appears that items are for sale that I can't actually get to from any of the categories. for instance, skate bearings appear nowhere other than the 'recently added items' list where they will soon fall off the bottom. and there are references to items in links that don't seem to lead anywhere.

One way is to do an advanced search and put in a price range from $0-$999. This should get everything for now.

It looks like you've found a flaw in the store software in that an item can be in no categories and therefore not easily accessible. I would suggest the addition of a misc. category to be the catchall/default so that each item for sale is in at least one of the categories.