Best Album Purchase, or Best Evaluating Record

I would just like to know what you consider your best album purchase ever, or your choice of album used to evaluate a stereo system.

My best purchase has to be about 300 - 400 classical records, for $300, that contained many mint shaded dogs, Living Presence, and blue Backs (among others).
Isao Suzuki String band (featuring Ron Carter) on Flying Fish direct to Disc.
I brought it to an audio show to play on the Caliburn table. The guys from Caliburn commented on how incredible the recording was. The music is even better.
The Fone jazz LP's are awsome as well.
"Boomtown" by David and David. Bought it at my barber shop for $1 last year. Killer sonics for a pop record. Darn good music to boot.

Ok, pretty lame. But hey, what's the best record YOU ever bought from your barber???

For evaluation I like:
Come Away With Me- Norah Jones
Time Out- Dave Brubeck Quartet
I have the David and David record too, and it is good for a lot of reasons. The lamest purchase I ever made was a Jay Ferguson cutout, back in my college days. At least it has Thunder Island on it!

I also have the Norah Jones, and the Dave Brubeck albums. Not only is the Brubeck a mono copy, but it looks like the previous owner used it for a Frisbee in the street.
The best ablum you could use in evaluating a system is the one that best represents what you like to listen to. If it sounds good that would be an indicator that you're on the right track.
Miles Blue. I own this music in five different media types, played on ss and tube rigs. The vinyl is still the best and when I go to dealers to check out new speakers, I use that as a reference. I take both the vinyl and sacd. A blu-ray will be available shortly. Wow.
I bought Rickie Lee Jones' debut album when it first hit the racks in Tower Records on the Sunset Strip in 1979. I think I paid $4.99 for it. Great recording, fine stamping, and still one of my reference LPs after all these years.
I like the Rickie Lee Jones too. Any Miles Davis sounds great as well. I just spun a copy of Relaxin' that was excellent. I haven't heard Workin' yet, but I will soon.
jazz at the pawnshop. if a component can't play this,especially the last track on side 1 without everyone in earshot dancing, it's no good.
best purchase has to be about 300 - 400 classical records, for $300, that contained many mint shaded dogs, Living Presence, and blue Backs (among others)
You are so mean :)

best purchase has to be about 300 - 400 classical records, for $300, that contained many mint shaded dogs, Living Presence, and blue Backs (among others)

You are so mean :)
I recently bought 70 Deutch Grammaphone classical LPs at $190. They are all in new/mint condition - no scratches, no molds, no play noise, no warps. Most of them not in popular category, which I prefer. I don't want to add another Beethoven Symphony #5/#9 into my collection. ;-)
bought an original Casino Royale in nm shape for $5 at a record show. Also bought a nm Die Beatles HorZu from the same guy for $5. He was going to knock a buck off the pair as well.
Whenever I do a tweak or an upgrade, I reach for the Diana Krall Christmas Songs LP, and not the 200g black version, but the 150g transparent red version. It sounds wonderful. It has everything--SOTA analog source recording, great mastering, female vocals, lush orchestrations, sleigh bells and assorted percussion.

I also have to give mention to "Class of '78," a direct-to-disc of the Buddy Rich Big Band. That's the record that launched my latter day vinyl craze. I took that LP and its companion SACD to my local high end store and had the sales guy spin them both through a pretty expensive all-Linn system. That was that and I haven't bought any digital music since, and I didn't even listen to any for over a year.
I really like the M&K Lp 'For Duke' as a reference recording..This LP really has some of the best sounds
recorded IMHO and shines on my system
Tracy Chapmans' self-titled debut album - Tracy Chapman, outstanding!
Original CBS recording of Abraxas by Santana. Absolutely gorgeous.
I use quite a few LP's. A number of Bill Evans (Spring leaves, At Shelly's Mane Hole - I don't yet have a copy of Debbie) Oscar Peterson Night Child on Pablo is fantastic. Brubeck A La Mode and Time Out, Athena's Symphonic Dances, Sufjan Steven Illinoise, Nora Jones, Feels Like Home (CLassic Reissue) Fiona Apple's Extraordinary Machine (just the title cut), Rickie Lee Jones Pop Pop and her first title (most RLJ sounds very good) Joe Jackson Body and Soul, Satchmo St. James Infirmary, Brubeck Discovered Again (a little boring) Paul CHambers Bass on Top. Greateful Dead's Reconning - a great live acoustic set. I also use, and get ready for this, Springsteen's Devils and Dust. I never get tired of listening to the title cut, and Reno. I bought that Suziki String Band on Bkonig's recommendation. It's really nice sounding but I guess I don't like it musically. I'll have to give it another listen.

For digital playback, Patricia Barber's Companion is my reference. I'll have to get that one on LP, though I know it's a digital recording.