I admittedly do not know much about the 1903. Feel like I should start learning about them already before the Wannemacher gun show.
How much could I expect to pay for a good one?
Are the sniper variants really rare and expensive?

Real A4s are out there but not common, or cheap. Fortunately the way Remington marked the receivers it's easy to tell real from fake.

Yup

The 03 has the rear sight forward of the receiver.  The 1903A3 has an aperture mounted on the rear of the receiver (a lot easier to shoot IMO).

If you want an example of one that would have really seen combat use, get a straight 1903...the reality is the 1903A3's saw relatively limited combat use in WWII.

I like the 03 better myself....Rock Island made much less than Springfield...so they tend to be more $$$.

As far as A3's....the Smith Corona's are fewer than Remingtons....

Remington also made a straight 03 early on, before switching to A3's....SC only made A3's....

Prices are going to probably $600 and up... A4 snipers, real ones anyway, $2k and up...

As far as what to look for...there are literally books on the subject...way too much do get into here...

Did I make a big mistake in turning down a Gibbs 1903A4 with a repro scope for $1500? If so... d'oh!!

Meh, seems a bit high for a Gibb's on the secondary market...they were pretty hit and miss too, the early ones, the scopes were pretty shitty....

I wouldn't pay that for a repo most likely made on a resurrected drill rifle with a Chinese scope of spotty quality...

My 03A3 is a tack driver but it will hurt you after about 20 rounds.

Vince

Tag for interest.

Hmm, I'm kinda worried about breaking an authentic scope since I would like to shoot the gun once a month or so. Are the repro scopes decent?
If I get an authentic 03A4 without the scope, is it plausible around the $2000 mark? Are there repro base/rings as well?

Didn't realize they were that rare/pricey!

The repro Hi-Lux scopes are good. They have released different revisions of the scope, make sure you get one that has the "G4" at the end (I belive that is the latest version).

Don't  forget National Ordnance!  

Belleau Wood, WW1, Marines against the Germans.

1,000 yds. between the woods the Marines were in and the woods the Germans were in.

The Germans tried to cross the wheat fields to attack the Marines.  The Marines were armed with 03 Springfields and GI ball ammo.  They started killing the Germans and 800 yds.  The Germans tried to cross that field 5 or 6 times that day and finally no longer had enough men to man their lines and were replaced by another German Army unit.  The reported to their higher command that they were facing "a battalion of snipers."

Nope, just some US Marines with bolt action iron sighted 30.06 rifles.  US Marines that knew how to use those rifles to the fullest extent.

Personally, I don't care for the 03.  The butt stock is too short for me (6'3" tall with long arms).  I can't wrap my right thumb over the comb of the stock and have to get my cheek down on the wood and my nose is on the rear of the receiver.  Mine just beats the snot out of me.  The 03A3 butt stock is much better for me, if I stick to the Springfields.  I prefer my M1917's over the 03's.  Longer stock, longer barrel, feels good in my hands, peep sights back on the back of the receiver.