Re: Any way to get the BioWare Signature Edition items?
The Signature Edition comes with a voucher to unlock the content. However, I had a quick look at my Signature Edition and it says the voucher is supposed to expire in 2012. I'm not sure if the voucher actually expires or if it's just there as legal safeguard should the online systems no longer work.
Once the content is registered to your account, you can just download, install and authenticate. The base game included on the Signature Edition is the same, with only the box art and the included voucher being different, so the content should work on all versions.
The Signature Edition was only available for pre-order, so I think a sealed copy would be difficult to find. I found one on ebay, and it's quite expensive. For only a few items and not even a guarantee that the voucher still works, I think it's a bit excessive.