The Math U See app is somewhat limited but it is portable and can be fun to use. It will allow you to play with some of the very basic Mortensen Math concepts and give you a feel for what the real blocks are like. Neither the app or paper blocks come close to the real blocks but they can help you understand what playing Mortensen Math looks like and it is a good alternative if you can not afford to buy the hands on blocks right now.
Here is a video that shows a mom’s overview of the app and another video advertisement for the app from the Math U See team. Both will give you a bit of an overview of how the app works and what it has to offer.