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There's no easy answer, I'm afraid, and if an answer looks too easy, I'd stay away from it. Building low-quality links might help in the short-term, but it's too high-risk in the long-term. Plus, if you're combining it with duplicate content, you've got multiple quality issues in play (at least, in Google's eyes - I'm not making a judgment calling about using product descriptions, which is very common). You say that unique text is proven to have worked, and yet it isn't an option. Why? If it's a matter of time/cost, I'd strongly consider not only the long-term ROI but the possibility of investing selectively. For example, you don't have to write unique text for every product you sell (or re-sell) - you could pick the top 10% of products (which may account for 90% of sales) and start with those. Even the top 1% would be a start. Small investments in the right places could yield large returns here. The other option that people don't like to hear but really is powerful is to consider more carefully focusing your link equity on a smaller number of products. The more products you list, the more duplicates you have, and some of those products are probably very poor sellers or have very poor profit margins. What if you focused your site architecture on 25% of the total products? You'd focus your authority more and each page would be stronger, relative to your competitors. One easy win is to make sure you're not dealing with any internal duplicate content (product options pages, search filters, etc.). If you're compounding external duplication with internal duplication, it's only going to make all of your problems worse. The internal duplication is much easier to solve.