About 10 years ago i got Loom the CD version fully boxed (Kixx budget version) new and unused for £2 at our local cash generator.
Oh and i got The Dig & Full Throttle double pack (white label) for £3.

LOL, I don't think anyone tried soulbringer, at least for more than 20 minutes. Historically, it's interesting because as far as I'm aware it was one of the earliest CRPGs with 3d graphics models using mocap, or something like that. Gameplay-wise, suffice it to say, you didn't miss much. Combat looks really cool, though. Otherwise, it played like a poor man's Neverwinter Nights.
The interplay fallout 2-pack was a nice set too. I have all the interplay shovelware comps, including the DnD one with a dozen or so older games. Great comp if you like the stuff.
That Age of Empires 2 + Conquerors case was a good deal. Oh boy do I ever like that one. Empire Earth is the only other RTS that's even in the ballpark for me.

Age of Empires: Collector's Edition - AoE + Rome and AoE2 + Conquerors = got it for 5 euros. :)
The same with Rise of Nations: Gold Edition.
The Orange Box for ~25 euros.
And Prince of Persia: Trilogy for 5 euros. :p

Impossible to say, really, I've found so many bargains over the years (I guess that's why I still go nuts when I come across a bargain bin, though I usually already own whatever's worth buying).
Though I remember finding the big box version of Planescape: Torment for 5 euros. That was pretty neat. There's tons of stuff like that, but it sticks out for some reason (possibly because the game was so amazing).

The Orange Box 10 bucks.
Every game I have purchased on here.
Elder Scrolls 4 Oblivion, Far Cry Predator, and Dead Rising for 31 bucks. All were considered 'new'.

Not sure... I think I was rather lucky with Final Fantasy for NES. Payed only $7 on eBay for it, with a dustcover. I also managed to get Realms of Arkana III, still sealed, for only $10.
Incidentally I got Realms of Arkania II for $20, not sealed, but everything was there. However the bastard who had packed the thing, had managed to tape the bubble wrap to the bottom of the box, which was irremovable without some cosmetic damage to the box.

Universe at War for €0. Yup just paid postage on eBay.

Maybe Brothers in Arms for 99CZK - which is something like 3 EUR
But I also got Commodore 64 with some cartridges with it from my teacher in school for free. I think he didn't realized, what that really is.
EDIT: Well yes, it was in 2004, so it hadn't so damned great value... but... its still Commodore 64 for FREE :)

Hehe well I didn't find it myself but 3D Ultra Minigolf Adventures on steam was a pretty nice price, 10 copies for au$1.30...

Oh yeah, that $0.10 mess up of theirs. That game is probably worth 10 cents anyways isn't it?

Well I enjoyed the first 18 holes I played. May have been the crappiest I've ever done at a round of golf but it was damn sure the cheapest!

One cent per hole is damned worth it. You can do worse at a video games arcade.

I still think 10 bucks for Orange Box on 360 was one of my best deals...

I got 2nd hand (but look like new) copies of Max Payne and No One Lives Forever 1, £1, buy one get one free from Gamestation (UK store).