Auto races are the only sporting events I attend these days. The prices vary by a wide margin. The F1 race in Austin will set you back about $1200 for a 3 day weekend pass in the main grandstand's "Club Level" to $169 for a general admission 3 day pass. If you want to drive and park at the track, that's another $200 for a 3 day parking pass. I have no idea what paddock access would cost for this or any F1 race. Probably best to bring along your first born son just in case the price exceeds the credit limit on your Mastercard though. But F1 is the most expensive series to attend. I'll probably attend the Petit Le Mans sports car race at Road Atlanta this year and a few other sports car races at VIR. Those are usually less than $100 for 3 day tickets. I used to live for CART IndyCar races... til the IRL came on the scene and fucked it all up (someone remind me to cut Tony George's balls off when we're both in Hell). You could get crazy with extras (paddock access, club memberships, pace car rides, merchandise, etc.), but most of the time those races ran about $200 for decent seats and paddock passes for 3 days. When my company was a sponsor, I could get into CART races and some Trans Am races for free. I really, really, really miss those days. No matter what you paid, it was so much fun.
As for bargains, I think that NHRA and IHRA drag races are the most affordable for what you get. You get to see tons and tons of races and you get a chance to meet the racers and see how they work on their cars for a very good price. Problem is, I'm not a huge drag racing fan.
Pals of mine that are baseball, football and basketball fans tell me that the prices have definitely had an affect on how many games they attend these days. They say MLB baseball is just outrageous now. And even college football is crazy if the team is a Division 1 upper tier team. IMO, it's too bad that a dad (a good average guy, not a hedge fund vulture with money to burn) might want to take his kid to some baseball or football games but he can no longer afford it.