Shelf unit like that retails for $300-400. The partition is $305.
Your units look well used and a bit rusty....do you have the key to the storage?
I'd put in Craigslist as $100 each, $150 for both together...Or Best Offer.
(If you're keeping the partition, then $100, OBO is about right for the shelf.....I'd take the first guy with 50 bucks cash)