Just browsing through the sale on
http://www.steampowered.com and noticed that all NovaLogic games are half price. I assume it's part of the sale which runs until 3 January.
You can browse the NovaLogic games via this link (it's not an affiliate link just a search link):
http://store.steampowered.com/search...gic&category1=
Even though Scott will kill me for advertising Steam, it might be a cheap way of completing your Delta Force game collection
oh and Happy New Year to everyone.