Costs are high because your paying for a Service as much as the game,
Check out this link http://iracing.com/membership/subscriptions.php?lc=2
Monthly 3-Month 6-Month Yearly
Price: $20.00 Price: $50.00 Price: $90.00 Price: $156.00
And that just gets you started with some basic tracks and 2 different cars. You have to buy more cars and tracks if you want to use them, but once you buy them they are yours for ever (at least as long as you are in the game), With each higher level subscription you get bonus bucks to buy more cars and tracks. Cars are about $15 each and tracks are $20-$25 each. If you finish high enough in the points you can win iRacing bucks that are good to buy tracks, car or your monthly fee.
One thing to note, it that you can access the service anytime, but RACES only run on the hour. so you can test, practice, or run a time trial just about anytime. You can only race on the hour, and qualify is every 1/2 hour.
Driving your starter car (The Solstice) really sucks at first, No ABS, no traction, no power, It takes a little while to get used to it.
I really suggest trying it for one month before sinking alot of money in to it.