Thanks for your reply Nicolas.
With regard to exporting and importing. I've had a go at that and it is not as straight forward as I'd hoped because all of the variants have their own record and the real product number only increases every seventh row - so messy for editing. Although I have been successful in copying editing and importing, it is very tedious and time consuming.
It seems to me that it would be better if the characteristics table itself also held the prices for each variant (or zero for no prices). In that way instead of a new product record being made for each and every variant. just one field on the product record could have the characteristic id which would link to all those variants and their prices.
Say for example I have a characteristic record called "Format"
and the variants within that are "Print" "Laminated Print" "Framed Print" (etc.) and also the prices 14, 18, 45 respectfully
(For variants with different prices you could simply enter another record "Format2" with the new prices.)
Because in my scenario there are very few price changes within these products.
Then the product record would be
Unique_id, Product_id, Product_name, et. etc. Variant etc. (and the variant would hold the id for "Format")
In this way when I export the products csv, given that each product has it's entire data on ONE record it would be so easy to duplicate/clone this and edit for changes. (it also means that each Parent Product record increments by one on each row)
And similar to your present import which allows new categories to be made on the fly you could do the same for new Characteristic records holding the variants (it would hold one dummy variant to be edited later).
These could then be edited later (even with an export import) to show the correct variants.
In my case this would only be about 9 records in this table.
This is better than at present, duplicating all 6 variants for each product on the products table and giving them each their own records.
Anyway, that's just my suggestion which as I say suits my purpose for selling art pieces.
Thanks for listening.