I'm happy to announce that PCPartPicker now lists external hard drives! Whether you're including it into your part list or looking for great external storage deals, we now have you covered.
This initial rollout supports desktop and portable drives ranging in capacity from 120GB to over 20TB. We are not currently listing NAS devices yet, but hope to support them in the future.
We're continually adding new drives to our listings. However if you can't find the one you're looking for let us know in the forums and we'll get it added promptly.