Sliding Scale / different number of class options /" Add-ons"!

We'd love to be able to offer different price point levels for folks who are self-selecting a spot on a Sliding Scale based on their income. Also it would be fantastic to be able to offer an adult class, say, but to have folks register for 4, 6, or 8 classes. Last -- we'd love an option wherein you can buy a ballet class and "Add-on" 30 minutes of pointe at the end, or a Baby Dance class where you can "Add-on" 30 minutes of Freeplay under the umbrella of that class. Thanks for asking for input!