Not sure if the answer is obvious here but I don't know much about finance, does 'spread' here mean the difference in the asset price from purchase/sale time (whether by market change or artificial markup) or the brokering fees involved? or both?
Any vendor will buy a good at say, $9 and sell at $10. In the US there are many pawn shops saying "We buy and sell gold!" - it's never at the same price.
#1: A smart gold trader will buy low, sell high.. they will buy more gold when prices are low and advertise to sell more when the price is high.
Brokering fees are not calculated in with the base prices, though it would be once it's time to calculate returns.