Unfortunately, the only gamestore I know in my city (not counting supermarkets and a book store whom I know it also sells games) doesn't have a bargain bin, at least not for pc games. But occasionally, they have good older games on their site or in their pc shelves. I already found Homeworld there for 11 euros, Brothers in Arms+Hell's Highway+ Earned in Blood for 8 and Medieval 2: Total War+ expansion for 5.

Fantasy Wars definitely qualifies. I found it literally in a bargain bin for something in the region of €2. Superb game for that price. I even bought it on GOG to repay the developers for all the fun. (or the current rights holder, whatever)

Yeah, about 10 years ago I saw "Planet of the Apes" in a bargain bin for $10 or so which came bundled with "Battle Realms" which I'd never heard of. I just thought I'd pick up the Planet of the Apes game to check it out after watching the movie remake. I never did play Apes enough to determine if it was any good as my system barfed for a while, but I ended up doing a reinstall and trying out Battle Realms and it was surprisingly good. It is Warcraft III like, but came out a good year or more before Warcraft III did. Nice gem. ;o)

Also, Dawn of War was bargain-bin for $2 and was pretty good.

I picked XCOM, Z, and Moonbase Commander out of the bargain bin. 2 bucks a pop if I am not mistaken. XCOM I already owned and knew about, but Z and MBC were nice suprises.

It ran great maxed (or almost maxed, not certain) on my machine at the time - Windows XP Pro 32bit, Core 2 Duo E8400@3GHz, 8800GT 512MB. This was around 2009.

Maybe windows update or GPU drivers screwed something up since then, not sure.

I got Fallout 2 and Septerra Core in a bargain bin. My uncle found Grim Fandango at one.

I purchased Neverwinter Nights Diamond from a Goodwill for $3. :)

I picked up Lethal Tender just because I remembered seeing its cover art in a magazine ad and I liked the way it looked. :P It's one of those FPS games made with the Pie in the Sky 3D engine, but it's surprisingly fun and ambitious for a game of it's time and quality. You can freely move around and explore the gameworld, there's a location-based damage system (i.e. getting shot in the leg would slow you down), there's a stealth and disguise system, there's a simple inventory system, you need to look around for notes that show secret routes, and so on.
Much later I discovered that it had a sequel, Terminal Terror, which has even more interesting features.

Found a cheap PS2 game called Seek & Destroy a while back. I was expecting something somewhat mediocre judging by the cover art but instead I got a decent action-adventure game where you could do silly things like mounting a chainsaw onto a tank turret. While it's not my absolute favorite game on the Playstation 2, it was still quite fun.

Some gameplay.

Yes...yes I do. I bought the game when it was around $30 USD and it's paid for itself many times over at that price.

As for bargains that surprised, the only one I can think of was a game called Medieval Lords, something of a city builder/economic sim. It had its warts. But I picked up practically for free and got a few good hours out of it.

Got Opoona, knowing very little about it, for $10. Turns out to be a pretty good RPG :3

Also, even though I'd already listened to it a thousand times (Nirvana's my favorite band), found In Utero at Wal-Mart for $5...WTF?

I haven't picked up many games recently from actual bargain bins, though I used to all the time as a kid. I suppose going on about whether or not I enjoyed those games isn't really relevant because I enjoyed practically anything that came on a disk and fit in my Playstation back then. With that said, I do rummage about online now for cheap, bad games (in terms of being panned by critics and often users too). I'm actually pleasantly surprised at how good a lot of these "bad" titles are. Though, whether that's because of my incredibly low expectations or actual quality is hard to say. I suppose I could very well just have a soft spot for terrible games.

Come to think of it, I think I enjoy most bad games as much as good games.. when they're bad in that sort of B-movie way.

Not exactly bargain bin, but I bought a new Wizardry 8 for $40 CAD ($30 USD) back in the day. It's the version with the printed manual too, so it must be worth a lot.

But I have the most special version - it contains 4 CDs. :p