Personally I never bought a mat as it is just an accessory and you can just use anything in the house or not at all. A timer would be good to practice for comps. But I didn't buy any of those and I was fine in my competition. If you have a budget cube then a midrange cube ($20~30 usually) that suits your needs (whether stability or speed etc) would be good. I'm actually looking for a more stable 3x3 as well! But just like what @TheEpicCuber said, just buy it if you need it. Remember lube too.Ok thanks
Oh yeah I want to ask you if I should get a timer and mat. Due to the pandemic, there are no WCA comps in my area but I might attend one in the future. I can get a gift at the end of the year so I'm asking if I should buy a timer and mat or a cube.