Eric, I think the media is $20, you will only need 1 copy
your VLK options will be
MAK (multiple activation key)
KMS (key management service)
I haven't used the latter, and it sounds like the former is what you are after.
Would love to hear from those using KMS about the advantages and hiccups.
I believe ASAP offers the VLA media, and I assume I will be able to obtain a Volume License Key from Microsoft for this purpose...