What do you mean by bargain? Something sold retail that's widely available or a one-off thrift store, garage sale, or ebay find?
Some of the best retail bargains that I've found are the Scott Nixon DacKit with the Blackgate parts package that Scott sold several years ago for around $100, the great-sounding Sharp EX-111 all-in-one digital receiver and CD player from Overstock.com for $75, a bunch of those Sonic Impact T-amps for $23 ea., the Electronic Tonalites Foreplay preamp for $100, the JVC ES1sl digital receiver for $140, the Sony SCD CE595 SACD/CD player for $125, and the Optimus LX-4 Pro speakers at $70 a pair.
All of these are musical and compare favorably to much costlier gear, so I consider them a bargain.
I'd say my Audio Note Kit One is definitely worth more than its price, but not really a bargain at $1300 shortly after it came out.
The Brian GT/Peter Daniel Gainclone kits are probably a great bargain, but I haven't built mine yet. If it sounds like the original Gaincard, it would be a great bargain, indeed.
Some of the best one-off deals that I've found were a Eico HF-81 that I got for $5 just before it was going to be thrown out at a flea market, a beat up Dynaco ST-70 for $10 at the same flea market a year earlier, a mint condition Dynaco ST-35 for $130, a Scott 299A integrated for $65, a Scott 222C integrated for $160, and an excellent pair of Klipsch Heresies for $140.
In the amazing AND free category are 7 Altec 405 4" drivers, 6 pair (12 total) of Altec 755 E drivers in mint condition residing in two original Altec PA cabinets, and a pair of the Electrovoice T350 tweeters. All of this was thrown in the trash bin when my workplace decided to upgrade its PA system. Luckily, I knew enough about the stuff to grasp it from the jaws of oblivion.
I never thought I was so lucky, bargain-wise, but clearly I came out OK. If I could only find a pair of vintage Tannoys for cheap I would be entirely happy.
Best,
KT