You could buy some flux cored wire if you don't have gas. Though that's not great for learning because it's more difficult to see what you are doing.
Don't practice with solid wire without gas - it just frizzes away into a spattery bubbly mess. You'll not get a good weld pool, blow a load of holes, and mess up the tip and shroud.
you can practise the motion without gas, its nigh on impossible to get a weld that looks even weldish, but I have done this just to get my hand in, so to speak, then when you do get gas it does feel like the practise made a difference, but really you could practise the motion without even having the welder turned on.
The problem with the disposable bottles from what i seem to have read here is they are a bit hit and miss. An industrial bottle with a quality regulator will give a solid flow of gas at a constant rate, with plenty of room to adjust the gas flow up or down as required. Try and source yourself a good deal on an argoshield type gas, there are a good few post on here about different deals from various companies, and you will find your welding improves in leaps and bounds
Whatever you're learning you really need to practise with the best equipment you can get your hands on. That way you can perfect your techniques without have to compensate for duff equipment.
Don't practice without gas:- you'll learn absolutely nothing about your welding. It's really not an option, sorry. You'll have to bite the bullet and spend dosh