Yes, you're right, a new Criterion barrel from CMPis only about $200, plus installation. (No one has NOS USGI barrels, except for a couple of smart folks who have them squirreled away.)
Don't worry about the color of the barrel not matching the rest of the Parkerizing. Actually, different shades of park is desirable, as that is typical for original rifles, assembled from parts in bins. Usually, an all matching color rifle is a commercial repark.
But, WarPig is right, too. I hope that you are right, that all that red stuff is just dried grease and not rust. That's because USGI replacement parts have become scarce & expensive, & it could cost far more than the rifle is worth if you find that there are many parts that are not usable. Let us take a look at it after you have cleaned it.
Neal