I'm not a real racing driver and I'll stay away from the debate over the pluses and minuses of each sim in the market, however I'll just point out the following regarding iRacing.
iRacing misses a bit the plot regarding its pricing policy (though I understand why they don't market it like that). Please consider the following:
1st rule:
For the base package, which IMHO should include around 15 tracks and 4/5 cars (see below), you'll have to spend around $220. This, for me, is the absolute minimum if you plan to stay for the long run in iRacing.
2nd rule:
The subscription for a year doesn't cost $99. If you are savy, you can take the regular promotions that lower the price to around $70.
After that, please bear in mind that you can gain as much as $10 credits for each season (4 season for each year), thus the subscription tends to get cheaper than that.
But, for that, you need to participate in different championships, that's why the base package should be as extensive as referred above.
3rd rule:
Stay away from "emotional" shopping (like when "this" car or "that" track are released). You should plan your shopping in order to get the 20% discount on items (when you buy 6 items at a time), even if it means that you'll not get right away the car or the track of your dreams.
4th rule:
You don't need to spend $600 for the whole contents. I mean, do you really have the time to race in road courses and in ovals? IMHO, participating in two different championships for each season is more than enough (a lot of people miss this, thus they tend to be very slow and have lot's of accidents just because they want to drive in
every race with every car).
If anyone has more questions about iRacing, I'll happily answer them after reading them