How much you capital you need is up to you. Trading is all in percentage terms & is the same (excluding fees).
If you invest $1000 & stock goes up 10%, you profit $100
If you invest $100k & stock goes up 10%, you profit $10k

You're targeting to make 7.5k/month = 90k/year. If you're investing, assuming a 7%.p.a. return over the long term, you'd need $1.28 million in capital.
But if you're chasing short term gains, there's no answer. You could put 1k today and tomorrow becomes 2k, or becomes 0. There's more risk involved. If you're not experienced day trading is pretty risky.