It is not an oxymoron. An item can be simultaneously seen as "affordable" and "luxurious". Since it's just a phone, anyone can save up enough money given enough

It is not an oxymoron. An item can be simultaneously seen as "affordable" and "luxurious". Since it's just a phone, anyone can save up enough money given enough time and/or external sources of money (e.g. parents), but that doesn't mean it's cheap (not luxurious) - "cheap luxury" would make an oxymoron, but this is merely "affordable".