If Alexander sold his salt to Ptolomy and Farzah in bulk, then it would be those men who would be the main beneficiary of the lion's share of the profit.
After all, the most profitable part of a business was being the middleman, having no headache about production, or about selling the product to the customers.
So if Alexander used these men as a middleman for his product, he would not be able to sell the salt at a premium directly to the customers but these men would be.
Though it could also be argued that these men would also have to bear the cost and logistics of selling the salt inland.
As for option two, Alexander did have a large number of candidates to choose from.
There was Thesos with its vast number of city-states, there were the warring states to his south and there was even Thebias who were his immediate neighbors to name just a few.