Many of us have been there. That moment when we have $182 in our checking account, we’re getting paid in a week, and we need $30 worth of paint, paper, or whatever (recent graduates in particular, I’m looking at you). In that moment, $30 is a lot of money, and you have to decide between (for example) seeing your friends at the bar, and buying the art supplies. 

But you know you can’t do both. 
This small, common situation is a decisive moment for all of us, though it may not seem like it.
The number of students I have had who tell me “I’ve been meaning to buy X for a while” so they can test out some new idea is staggering. “Meaning to buy it for a while” - do you know what that really means? It means that for whatever X months (and sometimes years!) you’ve been failing to pursue your dreams over 30 dollars. Over $100. Hell, over $400. 
In that moment, that $30 has become a barrier to the rest of your creative life. You’re not making your work today, tonight, tomorrow, this week, next week, this month - because you’re putting off buying what you need.
It sounds crazy, right? But I can speak to this because I’ve been there myself, and it took me a long time to learn better. When I realized small actions end up being the biggest obstacles to our creativity, I made great progress in my creative practice. 
Taking the time and money to get what you need, putting it ahead of other things you’d prefer doing, these are some of the biggest monsters you have to overcome as an artist… Because they’re the ones that trip up the majority of creatives, the people who always “wanted” to become an artist, but never found the time or money to pursue their dreams. They cause people to put off being an artist every month - and eventually, those months add up into decades. Don’t underestimate them.
So why do the little barriers tend to morph into the largest ones to our creativity?  Frankly, I believe it’s just another form of procrastination. We’re avoiding making our idea (yet again), because we prefer to daydream about it rather than sit down and do the work to make it a reality. And the sting of spending the money on something work-related compared to the fun and comfort of seeing a friend, going to lunch, buying a book, etc, is too tempting (after all, we’re tired, and could use a break). In reality, it seems so innocuous, but it’s a formidable foe to our development.
But - it goes even deeper than that. Fundamentally, I’m talking about consciously deciding your priorities, and living accordingly. 
What else are you prioritizing over your art, over your dreams? Are you mortgaging out your dreams of being an artist so you can afford better quality beer, nicer makeup, tools or hobbies? 
Stop. Prioritize your dreams at all other costs. Buy the supplies, and then use them (don’t hoard them!) Then fail. Then buy more, and try again. Trust me when I say you will feel empowered, alive, and better about yourself. That malaise, that quiet anxiety you feel before bed because deep down you know you’re not doing what’s necessary to make your dreams come true - it will only be eradicated by sacrificing for what you want and believe in.