if you get the funds i would say get a weight bench and 2 squat stands(better a rack but it takes up space) and a barbell set and train when you want and you can train how you want. No time limits and stress. I agree with training arms on their own. Arms are better trained with supersets.
Yes! buying weights it's a smart move if you have the money and you lack the time. I bought an ez bar, a par of adjustable dumbbells and 50 kgs in plates. I can train shoulders and bis really good, tris mmm not really, I don't like it but I train them at home anyway. I will buy a good bench but right now I'm still a student and I don't have the money, so i'll have to wait a couple of months to buy it.