Thanks for the suggestion CapnScurvy but luckily, Ubisoft is having a 75% off sale in most of their titles from today 'til the 24th on Steam. I already have the core SH4, and just got the U-Boat Missions Add-on for about $12 USD ($19.99 Before).
Oh and I just installed TMO..just WOW. I can't force myself to do anything right now but play.