I would match your projects to the number of inputs / outputs you can get.
Yes a shield is expensive but it is ready built and so it time is important and your hardware skill level low it should be your choice.
I myself would use multiplexers and port expanders.
The 4051 will give you 8 analogue inputs, in this project I used two to give me 16 inputs, with the four on the board this gives you 20.
http://www.thebox.myzen.co.uk/Hardware/MIDI_Footsteps.html
On the digital side then a MCP23S17 gives you 16 I/O per chip and it is easy to add up to 8 chips on the same SPI bus. Again the same project gives you and example of using them.