How big should my target market area be?

[Kgodisho Mononyane]

Hi BP,

I am a real estate wholesaler in South Africa and I currently focus on wholesaling real estate in Johannesburg. Johannesburg has a land area of 1645km^2 and a population of ~6 million. I am not too sure if this is too large of a surface area to for wholesaling so I thought I could get your opinion on it. How big of an area do you have as a target market area? Thanks in advance.