OOTP tends to go on-sale during All-Star weekend, in years past it goes 50% off, so 19.99.You can also get last year's version for that price today if you'd like. With OOTP, depending on what you want to do, getting the previous edition isn't really a dealbreaker.
If you're someone that does custom leagues or plans on playing a franchise 30 years into the future, the roster differences for your start year will basically be moot in a few seasons anyway. OOTP is a great game but they don't really add a ton of features year by year and 17-18 wasn't a massive jump.