Making extra profit from orders

I'd like to buy and sell items which will be imported. I won't be importing bulk but rather will advertise an item and buy it once I have an order for that particular item. I will be charged about R285 to import. So if I buy an item that costs e.g. R300 my total will be R300+R285=R585. And i'll add a profit to it. e.g.R50 which will make the item R635. I'd like to know if this is permissible Islamically? And if I have 2 orders, each will pay R635 but since the order will go in at the same time I'll end up with more than R50 profit.