Agree entirely with your summary - lots of good advice.
The amount of actual content on the priceonomics product pages is super thin. google is not going to be a big fan of throwing out every page of search results into the index - you're pretty much ONLY creating duplicate content at this point. also the taxonomy has a ton of copies of what is actually the same item, depending on how it was written in the listing.
Sorting the taxonomy into distinct products and then adding some sort of content to beef up at least the category pages, which right now are 100% navigation, would be a big step forward. Lots of things you can do going forward, in thinking about this vertical, it's an interesting market space for SEO, lots of challenges and possible strategies.
I'm assuming eventually some sort of comparable product cross-linking will be built into the system?