sampling methods - randomness sometimes a challenge



Hi everyone,

I need your advice about a sampling method that might work in this quite specific context. The story goes.. I need to conduct a survey in local fruit markets in Africa.

Most of the fruit marketplaces are street markets and I cannot gather a list of all the people that trade in the place because it is not 'owned' or administered by anyone specific. As I see it, a simple random sampling method in which I hypothetically would draw a list of vendors and choose survey participants randomly is impossible because the vendors are not registered anywhere.

What would you do in my situation? Can I randomly select in a different way. For example: going there every day of the week, drawing a map of the marketplace, assigning numbers to the fruit stands and using a random number calculator? Would this be acceptable statistically?

Thanks in advance