Hello sir,
How old your trees are, calculate the number of fruits weighs 1 kg, randomly select 10 trees out of 100 calculate number of kgs in branch and number of kgs/tree then(While selecting 10 trees try to have good combination of good yielding, medium yielding and low yielding trees) you will get avg kgs/plant then multiply by number of trees you will get rough estimate yield/100 trees then get the whole sale price per kg multiply by total yield get estimate then invite two to three buyers ask for there price and sell.