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Massive differences. What's the substrate, what type of paint, how many square meters.
For a one off job you probably don't need a fancy frame but it might be worth getting a decent roller sleeve.
There are so many choices it's hard to narrow it down for you, I have at least 30 roller sleeves, 10 frames and maybe 10 buckets and trays. All to suit different circumstances.
The most general starter type for emulsion on walls would be a 9" roller and tray set.
I don't use the trays for whole rooms, I prefer a bucket and an extension pole. I would also stick to sleeves from brands like Purdy or similar but I get a lot of use out of them. There are lots of different textures to choose from depending on the condition of the walls.
Is there a decent paint roller I should be looking for, or are they all the same?