$300-400 per month would be a very good investment if you can afford it. But since crypto investment is very risky, you must have the ability to lose those dollars.  But currently, since the price of other coins, including Bitcoin, has already gone up a lot, investing in the market will be much more risky now. So again wait for bear market and from that time every month you can invest such amount in bitcoins and other potential coins.  In that case it will follow the DCA method and you will get a good savings after a long period of time as well as a huge profit.