The Sony MDR-ZX110BCE and MDR-ZX110WCE headphones that I mentioned earlier for R249 each would be excellent options for you. They are compact, lightweight foldable headphones with an inline microphone so you can easily take calls. The built-in mic allows you to chat with friends while listening to music. Both models come in under your R300 budget and have great reviews for comfort and portable use. Let me know if you would like any other recommendations!
