A friend seen a Martin Indian trombone at a antique store.

Might be Indiana.

Looks rough

Wondering if it is a decent model or a beginner horn?

Indiana was the Martin student model at one time. I have a bell from one and it plays pretty nicely, although not as nice as my Imperial or the Committee I used to have. There is some schizophrenic background to the Imperial, which was a pro model before the advent of the Committee and a student model later. Premium Martin trombones were the Handcraft, which were specially selected pro models.

Thanks