Is EQ Titanium Required? Or can you use another version?

[Bastir]

I searched for the EQ Titanium client and found that it averages $60-$100 on Ebay and Amazon. I am not interested in an illegal download, I read the forum guidelines and am aware so please understand that's not what I am asking. What I am curious about is on the EQEmu site they say you can use any of the following

Everquest: Titanium Edition (Retail from the CDs)
Everquest: Secrets of Faydwer (Retail from the CDs/DVDs)
Everquest: Seeds of Destruction (No longer available by legal means)
Everquest: Underfoot (Download-Only from Steam - DOWNLOAD HERE∞)

However I always see here for this server that the Titanium version is required. So before I plunk down $60+ I want to make sure it isn't possible to hop onto steam and do their download of underfoot for $20.

I played on Vallon Zek when it launched until around 2003 and that is why I am really interested in trying out this server and not the abomination that EQ has become.

Any help would be greatly appreciated.

Thanks
Bastir