You can or cannot start your mining with $300. It depends on the equipment and tools you have on ground. First if you do not have a computer with a powerful GPU such as Alienware or GeForce or any of those gaming PC then you need to buy one. The average price for one is within $700 for a new one and $400 for a used one the last time I checked. If you do then, you are half way there -  the next thing is do you have electricity or better still you may need to look towards alternative sources of energy to power you mining operations. I know you are starting small so you do not need anything elaborate. You may need to build a 5500kw battery bank off of one 360w solar panel that can power your apartment. The estimated cost for this is about $1200 on my equipment. This would be a one-off thing and you wouldn't need to pay high electricity fee monthly. As you can see, the $300 is not enough to start up, you need to review your budget.