Antoine-Joseph Sax
I’m doing a little experiment, of sorts, with this post. Yes, you’re going to get a lot of great pics. In addition to that, though, I’m doing a collaboration with Helen from Bassic-Sax.info regarding collecting the saxophone. I thought this would be a good place to start!

Adolphe Sax patent drawing from French patent #3226 (March 21, 1846).
This picture taken from Selmer.fr.
In order, the instruments sketched are the Eb baritone (called an “Eb tenor” on the patent), C bass, F contrabass, C subcontrabass (called “bourdon” in the patent), tenor, alto, soprano and sopranino (the patent says, “[These instruments] are in the same keys as the preceding instruments at the octave — and fifteenth — higher”).
Here’s another portion of French patent #3226:

Full text page from Selmer.fr.
Mouthpiece close up and text from RascherMouthpieces.com.
The translation of the mouthpiece description is, “The mouthpiece of the bass saxophone. The other mouthpieces are then of the same proportions; one can, of course, make them a little smaller or a little bigger, if one should wish.” Amusingly, the proportions aren’t listed.

1843-1846 Adolphe Sax Eb Baritone
This pic from AMIS Newsletter, Vol. 37 #1 (Spring 2008). Page 12.
The oldest known surviving saxophone is the above baritone, which dates to around when the saxophone was actually patented. Other documents have mentioned that the saxophone was shown in public on both on February 1844, for a performance of Belioz’s “Chant Sacre,” and in December 1844, for a performance of Kastner’s “The Last King of Judah,” so the saxophone was around for at least a couple of years before the actual patent was filed.

s/n 40687 (1878) Eb Sopranino. Refinished.
From William Petit via TheSax.Info Gallery.
Depending on who you read, the horns produced by A. Sax were:
* Eb/F Sopranino (“Eb/F Soprano”)
* Bb/C Soprano
* Eb/F Alto
* Bb/C Tenor
* Eb/F Baritone
* Bb/C Bass

s/n 6437 (1849) Bb Soprano. Silver plate body, bare brass keywork.
From Mediatheque.Cite-Musique.fr.
I’ve personally seen:
* Eb Sopranino (“Eb Soprano”)
* Bb Soprano
* Eb Alto
* Bb Tenor
* Eb Baritone
* Bb Bass
Canadian musician Paul Brodie owned an Adolphe Sax F alto, which may have been the only Sax-made F alto in existence. The horn was featured in a Saxophone Journal article several years ago and the “Alto en Fa” engraving is quite apparent. A very reliable source told me that there’s a C tenor on display at a museum in Germany. I’ve heard people mention that at least one of the four surviving Adolphe Sax bass saxophones is pitched in C, rather than Bb, but I haven’t seen one or the engraving from one. I tend to believe that the “C bass” comment should really be in regard to the ophicleide-shaped saxophone prototype, of which there are no known extant examples (see my comments above).

Adolphe Sax Eb alto, bare brass finish. s/n 16149 (1857). From the National Music Museum.
Based on my Internet searches over the past few years, I’d say that the most common A. Sax instruments are Eb altos and Bb tenors out there, followed by Bb sopranos, Eb baritones, and Bb bass. I’ve only seen one Eb sopranino and no instruments lower than a Bb bass. C and F instruments are extremely rare. Also note that A. Sax almost always engraved the pitch of the instrument on the horn, so if isn’t engraved “Alto en Fa,” (for instance) it’s not an F alto.

Adolphe Sax Bb Tenor. s/n 23049 (1861). From the National Music Museum.
The finishes I’ve seen the most often are bare brass and silver plate. There are a few horns with silver-plated bodies and brass keywork. Gold plated horns were almost exclusively made for various exhibitions, so they’re quite rare.

Adolphe Sax silver plated Bb Bass. s/n 39789 (1877). From the National Music Museum.
In 1867, A. Sax’s original patent expired, so quite a few companies started making their own saxophones. In 1881, A. Sax obtained another saxophone patent that, among other things, increased the keyed range from low B – altissimo Eb to low A – altissimo G. However, it’s possible that there was only one — or one set of SATB saxophones — that A. Sax manufactured with this extended keyed range. In any case, I have not personally seen any of these instruments with the extended keyed range, but I know some people who have.

1872 Adolphe Sax advertisement. From Revue et gazette musicale de Paris via Musicology for Everyone.
Note that A. Sax instruments built prior to 1859 can be in a variety of pitch standards. In 1859, France created a new standard, where (concert) A=435hz. Low Pitch, the current intonation standard for most of the world, is A=440hz. Putting this all together, pre-1859 Sax instruments may not play in tune with modern instruments. Instruments produced after 1859 can play in tune with modern instruments, provided you have a good enough ear.
In general, a really good condition A. Sax alto will fetch a little north of $10,000 US. Even poor condition horns can still be worth in the $2,000 to $2,500 range.