Buy a little bit of bitcoin every week don't care if it's a $1, $5, $10, $100, figure out what you can afford every week and buy it, get rid of unnecessary expenses or whatever you can think of getting rid of and spend it on bitcoin
5 to 10 years if you buy some every week you will be a multi millionaire
Bitcoin is a high risk and expensive asset. So one really finds it hard to buy the whole bitcoin because of its highly expensive value. Hence, buying it in a small scale basis is more advisable so you won't feel the burden of buying or investing all in. You can do it weekly or monthly, it depends as to when your income comes in your wallet. But one thing is certain, through DCA, you will achieve a single whole bitcoin in time. That works for me and might work for others as well.
Save so you can invest. That's the basic rule prior to investing. And always do what is right, invest on an amount that you are comfortable of losing.