Steve:

I've never used it but there is a feature in PO called Contract pricing. This feature should allow you to maintain pricing by vendor. You might want to check with SOftrak to see if this feature will survive the transition to their PO replacement.

You should be able to use Alternative price lists. I've used this to maintain costs in US Dollars for my Canadian based multi-currency clients, but then this is only a single price list for all vendors. There is an option in PO Company Profile Interface Options Tab called 'Use IC alternative price lists'. In Payables you can assign price lists to vendors (hopefully this is not a multi-currency only option).

I'm not aware of any way to make the item specific instructions variable by vendor.