Commit to + inf vs + -ing

Solution 1:

Traditionally one commits to a person or thing. That is, one commits to a noun.

commit verb (PROMISE) C2 [ I or T ] to promise or give your loyalty, time, or money to a particular principle, person, or plan of action:

Like so many men, he has problems committing himself to a relationship.
The government must commit itself to improving healthcare. Once we have committed to this course of action there is no going back.

https://dictionary.cambridge.org/dictionary/english/commit

A gerund acts as a noun equivalent, so we can say, "He commits to VERBing"

In its traditional form, we don't commit infinitive.

Answer

I see "commit to buy" as an error. However English is always evolving so it may become standard in the future.

EDIT

See the comments below. The phrase appears to be standard in the world of commerce.