Here is a sentence I've got on my textbook.

>I **was buying** a new washer because my old one had broken down. I ordered a model that was in stock and available for next-day delivery.

I can't understand how it is possible to use **was buying** in the above sentence, which is really unfamiliar to me.
I think the following sentences is more familiar form to me. 

>I **was thinking of buying** a new washer because my old one had broken down. 

>I **was shopping online** for a new washer because my old one had broken down.

>I **decided to buy** a new washer because my old one had broken down.

So, I'd like to know what exactly '**was buying**' means.

Could you let me know why the 'past continuous tense' is used?