How to Buy an Option - Bid/Ask Spread
The Bid/Ask on an option operates just like a stock.
When buying an option, you will always pay the ask price. When selling an option you will always receive the bid. The spread between those 2 prices is taken by the market as a profit to facilitate the trade.
The following example is a call on the Exchange Traded Fund, USO, United States Oil. If you were to purchase this call in the example you would pay the ask price, $5.80. If you were to sell this call you would receive the bid price, $5.40. Volume traded in this example was 15 contracts.
Choose options with volume to assure you the best possible spread pricing.
You may place your price between the bid/ask to try save on entry costs.