Well, if you already have a computer, you could just write the whole thing yourself. Or get a really good, really talented friend to do it for you.
I you don''t have a computer (of your own), you can do one of the following:
wait a year, saving up your money, and buy one. get a job
But seriously, I''m making a game and it''s only costing me the price of electricity for the computer. If your idea is unique (don''t have to pay for the rights to use it) and you''re doing the work yourself, it shouldn''t cost anything.