After some years of just downloading the 3D models' files and putting them all toghether in the cauldron, I realized that I lost control of what I have available for my runtimes, what a product actually looks like and so on.
So, I decided to rebuild all my products' backup...
It was definitely a long and tiring job, but I already enjoyed the results and I'm happy I did it.
Maybe it can be of inspiration to someone, so here is the way I am following now:
I have folders for the various stores (DAZ, HIVEWIRE, RENDO...).
Inside these folders, for those I have a lot of items in, I tried to recreate a hierarchy similar to that of the separate runtimes I created to use in my programs (various versions of DS, Carrara and Poser).
So I have folders like: animals, chars_base, chars_injectable, vehicles, wearables... and so on.
Inside these, for each product I create a folder named after the product.
Inside the folder I put the model files and a PDF generated from the online store page of the product. If the text of the PDF is not selectable (as it happens to me for Daz stuff) I also copy the text from the original HTML and paste in a "description.txt" file.
Optionally, I sometimes save here some interesting promo images and an additional "info.txt" file with my annotations.
When a product requires another one to work, its folder goes inside the required product's one.
When I install a product, I add a "installed.txt" file in it.
This way, I can count the directories (excluding the categories ones) to know how many products I have; and the installed.txt files tell me whether something is installed or not.
I know it can be a hard work, but for me is was worth doing it... ;-)