Ithaca didn't make magazines for the WW2 contracts. The magazine contractors were:
Scovill. MS Little. Risdon. General Shaver, which was a division of Remington Rand. Colt also made magazines for delivery with their pistols.
To identify the contractor, look on the top of the toe of the magazine base for a letter.
L...MS Little
R...Risdon
S...Scovill
G...General Shaver
Unmarked...Colt manufacture
In addition, some are marked C-L or C-S ,etc. These were made by the vendor indicated for a Colt contract.
Value? Not so much. I recently bought 10 WW2 contract magazines that were in new or near-new condition for 15 bucks a copy. I got a deal for buying the whole lot. Not sure what they fetch in used condition.