This is where the journalist is one worth bagging out here for not doing their homework.
For not spending just 2 minutes on google to search for Transformers collections (to come across sites like TFW and Seibertron that have sections for fans to post up their collection photos), and for not looking into the assumption that there is only "10,000 collector items worldwide" which they have included non-toy items in that figure.
First off, there are now over 10,000 Transformers toys that have been released by Hasbro and TakaraTomy (some are identical out of packaging, but a collector of sealed toys can claim one from each company if the packaging is different). That's a fact that can be verified through some lengthy counting on tfwiki or a quicker count through Soundwave's Oblivion (which lists both).
Licensed merchandise (which includes comics and "collector items" ) is beyond estimation, and would be impossible to count, because every year, every country, releases/approves of hundreds of licensed items.
Its' a nice article for the non-fans out there to go "wow" over, but for us dedicated collectors, it is full of errors and exaggerations by the journalist.