"I am buying either purple or blue trousers."
Translation:Kupuję albo fioletowe albo niebieskie spodnie.
Maybe in speech, but that's not something that I would accept here. And it could put some weird stress.
Maybe you're just on the phone and you're answering a question 'what are you doing?' - Kupuję spodnie... albo fioletowe, albo niebieskie... (kind of loud thinking with mentioning the colours)
Or maybe you're arguing with someone: Like "KUPUJĘ spodnie! (I'm gonna buy it whether you like it or not) Albo fioletowe, albo niebieskie!" or "Kupuję SPODNIE! (even though you wanted me to choose a dress) Albo fioletowe, albo niebieskie!
I see. Because of the declarative nature of the statement, putting kupuje spodnie puts unnecessary emphasis on the act of buying which could be construed in the ways you mentioned. If I am understanding this correctly, even though word order is a bit loose with Polish, placing particular words towards the beginning of a statement creates more emphasis?