You can try
www.nationalrail.co.uk to look up individual train fares. For instance, return from Crawley is 21.70 per day or 108.50 per 5-day work week and takes approximately 50-60 minutes.
You'll have to contact the individual train companies for season ticket prices (which lhoward was kind enough to providea link to you for).
Train pricing is complex and can very much vary from person to person, even if they are commuting from/to the same station so that's why you may not have received many responses to your questions
Something worth nothing is that season tickets are not always the least expensive or most convenient option in that:
1) the prices are calculated to include travel on Saturdays and Sundays, when most commuters won't be travelling, and
2) the price of a yearly, 6-month, or even monthly ticket can be an enormous amount of money to layout at once, though many companies offer loans to their employees to pay for train tickets and then deduct the amounts from their pay cheques.
You would have to plan out what would be the most economically way for you to travel. For instance, I live in London and work north of the city but both the weekly and monthly season tickets are more expensive than buying 5 day returns tickets to cover travelling to work each week. I know that doesn't make sense but it's the way the system works.
The 6-month option was break-even and the yearly ticket would have resulted in some savings but the amount was small and I felt annoyed about advancing the train company what essentially amounts to a rather large interest-free loan without a more significant savings on my part.
Policies vary among the different train companies so its best to do some research before you decide where to live.