Building blocks for RDF

If you were going to create the RDF classifieds, there are some RDF building blocks you’d like to have.

Each for-sale item will have:
– A price.
This is a semi complex item. What is the actual price? What currency is it in?
– Shipping terms
Paid for by seller? How much? Paid for by buyer?
– Category
Presumably, robots will want to know how to categorize this. There is an RDF Taxonomy module which leverages the DMOZ categorization scheme. I hope dmoz promises to never change the taxonomy? :-)
– Contact info for seller
Contact him by phone? By email? FOAF is probably the answer for this one.
– Location
Where is the item?

And, these aren’t new ideas.

I wish there were standard building blocks for things like prices and such though.