How much to invest, what is the ideal copy value?

There is no perfect value for a copied portfolio. However, with a large number of companies that someone may have in the portfolio, the copy value, e.g. $200, may not be optimally distributed in the copy.

Therefore, I recommend choosing Popular Investors with less than 50 positions and investing larger amounts. If you believe in a particular strategy (yours or the Polular Investor you have chosen) it is a good habit to increase the value of your capital regularly for many months. You can further dive in this topic here