If they are kickass quality articles then post them on your own website.

If they are crappy then give them to your competitors.

If they are in between then improve them to kickass quality.

Those pen offers are very very similar.  Identical product descriptions except for perhaps number being sold or color or width of the tip.

If these were on my site they would all be on the same page.  One page to concentrate/conserve the linkjuice.  One page to make thicker content.   One page to present all of the options to the customer at same time.  (PITA to click between lots of pages to make up your mind as a shopper).   One page to make maintenance easy.

I am in desperate need of a starting point.

You start by doing what most other ecommerce webmasters are not willing to do....That is..... Write Unique and Substantive Product Descriptions.

The number of categories on your blog can grow over time if you write about a diversity of topics.  To justify a category you should have a few existing posts in that category or anticipate generating a few posts within a reasonable amount of time.

Extremely active blogs can support, and probably should have, a large diversity of categories simply to organize the content better and gain keyword reach in the search engines.

Another factor is the power of your site.  If you have a new site without a lot of power then busting out 100 categories could be like dead weight on your entire site.

I have a blog that over the past several years has received 25 to 60 posts per week.  It has over 150 categories and each post goes into at least two categories (one for geographic location and one for topic area).  Most of the blog's search engine traffic flows in through category pages because they rank well for high traffic terms.