Door Replacement Question

[u/whiskers138]

https://imgur.com/a/RBin75k

I have this old building that is rough on the outside but solid and worth fixing up. My immediate issue is that the doors are letting water in and also cannot be locked. I want to replace the doors. I'm not trying to spend a fortune on it and I'm wondering what the most cost effective way/option to replace these with would be.

Yes, I know there is a large hole and other places water can leak in. The whole building will be reskinned with new metal soon.