I'm looking to purchase a bike (probably second hand) and I want to make sure that it'll be easily repairable in the future for at least standard maintenance stuff.
Thing is, I don't know anything about bikes- I've heard people say off hand that modern bikes might perform better but are less maintanable, is this a thing? What qualities/features in a bike tell me that it'll be easier to maintain in the long run?
I would recommend any bike with 8 or 9 speed in your budget that you tried and like to ride. Add the cost of a good U-lock and lights. As it eventually get stolen, save for a next bike.
8/9 speed parts are robust, abundant, and cheap, and maintenance is easy.