If you are going to use Apple Configurator to deploy Apps, (which I do not recommend, see Configurator | SchooliPads). You should start with Free and try to keep it that way. Here's why:
If you look in the picture above, on the right hand side, you'll see the word “Free” or a number. If you look next to Pages it has 108, that's how many licenses I have left to deploy, supposedly. It actually stops me at 69 because of my not understanding Configurator in the beginning and trying to split a spreadsheet between 2 locations. Again, see my post linked above.
Anyway, if you look next to Pinnacle, it says Free. If you find Pinnacle in the App Store the price is actually, $12.99. However, when the app was launched, they had a big sale and offered the app for free. That's when, with the school account, I “bought” it. Because of that, it will always be free to me and Configurator, allowing me to install it on any device I connect to it in Configurator, even after an update. If you buy the app and it later goes on sale for free you will never have that option to buy it again at the free price. You will be forever locked in to Apple's license spreadsheet format to use Configurator.
My advice is to watch for the apps you want to go free before committing. Apps Gone Free, mentioned in an earlier post is a good place to start, you can even request an app to go free from them. There's also, appshopper.com where you can place an app on your watch list and get an email if the app changes in price.
Please comment if you found this helpful or if you know any alternatives to this method.