Ithaca 1911A1 value

Have a line on an Ithaca 1911A1 but it has some modifications done to it. I have not seen it and won't see it until next week but the guy wants $750 for it. The front and rear sights have been replaced with a taller front and an adjustable rear sight and the magazine release is missing the screw. Now, assuming that all other parts are USGI and not replacements and the markings are intact and not buggered up, is $750 out of line since I'll have to buy the parts for replacement and have them put on? Are USGI front and rear sights even available at fairly low prices?

I know little to nothing about 1911/1911A1's but want one just to have. It don't want a collector piece and couldn't afford one if I did. But, I don't want to pay too much for something that is not worth what I paid either.

Even though it is slotted that is not a screw in the magazine release. It may be broken off down in the mag release by someone thinking it was a screw.

Roger that. If it is broken, how difficult is it to remove and replace? Any thoughts on value?

If the magazine catch operates normally, the slotted part of the magazine catch lock may be broken off. If it just doesn't have the mcl, the magazine catch shouldn't stay in the receiver.
If the slotted part is broken off, you may have to drill out the part that has lock on it in order to remove the magazine catch to install a new one. The mcl has a pretty stout little spring on it.

https://www.milsurps.com/images/impo.../200bq6v-1.jpg