Hold in mind that the money you save by buying an older model may be lost in the long run when you need to upgrade sooner to run newer iOS or app versions. It's a balancing act, and a matter of preferences. Just want you take it into consideration.
Like Moonlit I'm assuming you mean the older iPad Mini, since the iPad 1 (I?) and 2 (I I ?) are full sized, and won't be easier to transport than any other older model full sized iPads.
The new iPad Air, though, that's significantly smaller and lighter, though not as small and light as the iPad Minis.