If it's all Eddy parts, with a plausibly original barrel and blued metal, that really ups the value. Many ERA's were rebarreled, which is where the origin of the "Eddystones are brittle" story is found (I won't go into the long boring details here unless you want to know, lol).
A "typical" WWII rebuild with mixed parts, parked metal, and replacement stock, I'd guess about $400-$500. CMP sold such rifles for $500 plus S/H and they went fast.
Subtract for finish wear, rust, bore problems, etc.
"Original" means many things. To a hard-core collector, that means the rifle has all the same parts and finish it had when it left the Eddystone factory in 1918.
To many, it means it's not been touched by "Bubba", the infamous sporterizer of military guns. Could be rebuilt and arsenal-refinished, but it's not been structurally altered.
Guns that fit the first definition of "original" are few and far between, and thus command higher prices. Guns in the second group are much more common and don't bring as much money.
A completely original Eddystone, with proper barrel (and date for the serial number), blued metal, good finish, Eddystone stock in good condition, that would probably be a $600-$800 rifle (or more, depending).
A WWII rebuild with a JA or other brand barrel, green or black parkerizing on the metal, and a military stock in decent shape is a $500 gun.
Add a bad bore, rust, pitting, or any number of structural blemishes and you've got a rapidly declining price.
I bought a Winchester M1917 at Cabela's for $350. It is in a refinished (but unaltered) stock that can be resurrected for the cost of some linseed oil, has mixed parts, and dark park on it. Also had a pumpkin-orange bore when I bought. A wire brush and some Hoppes made it shine like new. Shoots like a champ, too.
That rifle (#157) should sell for $400-$500, but at an auction, anything is possible.
There is a possibility that, with it having a JA barrel and being an Eddystone receiver, that the receiver is cracked. The possibility is very small, but it's possible. The only "easy" way to test for it is to soak the receiver in kerosene and then see if any is left in a crack when the surface dries. Can't do that at an auction, though.
I wouldn't be shy of an Eddystone, but I would be at least a little cautious with a rebarreled Eddystone. They SHOULD be checked by a smith or at least via the kerosene test before being fired, for sure.