You don't need to buy a whole 1 bitcoin if you think its expensive and your funds is not enough to buy that volume. But accumulate base on what you can afford to spend since for this you may now start to participate on anything you want to happen on the bitcoins you bought.
Also it seems you don't have deep knowledge about it since you get afraid with certain dumps to happen so maybe much really better for you not to decide yet to buy since your situation is not good so better try to figure out on what is your intention on your investment since if you can create some plans or have goals maybe for that you can make strategize your bitcoin participation then can able to earn with it in future. So for now try to learn a lot of knowledge so you will not get panic on the dump and will not see bitcoin as expensive asset to have.