Thinkorswim.com lets you can download their trading software for free. Their analysis tools include a feature called "thinkback" that provides past closing prices for options.
An option's value is determined by several factors:
- price of the underlying
- strike price
- time to expiration
- implied volatility
- dividends
- interest rates
You have to consider all the "greeks" and even then, understand that they can change by the minute. If you're looking to...