A similar way of thinking about it: how many days' work will it be to complete the work? Assuming 4 cards a day if you're working hard and quickly but aren't yet very experienced, that's 75 working days. Assuming that's full time, that's 15 weeks or about 3-4 months' full time work. Maybe 2-3 months since you'll get better at bashing them out fast.
So, three crucial questions:
- Can you live on $200-$500 for between 2 and 4 months? That's going to be somewhere between $50 and $250 a month, or around $12 to $55 a week.
- (assuming that there are very few other jobs going) Would that small amount of money realistically improve your life much over how it is at the moment? How much?
- The crucial question: if you're bashing out business cards at this rate, how many of them are likely to be good enough to go in your portfolio and improve your employment chances?
Think about the opportunity cost of taking it: what you could be doing for those 2-5 months if you weren't bashing out piles of business cards every working day. At that rate, for that time period, you should probably think of this as more like an unpaid internship than employment or a freelance job. That amount of money weekly is close to the few $ a day most unpaid interns get for travel and lunch expenses.
My suspicion is, that taking this wouldn't improve your financial situation, and would worsen your future prospects because, instead of being able to take up other ways to get practical experience such as self-initiated or small-scale projects that improve your skills and portfolio, you're stuck soullessly bashing out business cards at a rate where it's simply not possible for them to be better than mediocre. Also, in general, beware of exploitative clients who don't value your time - they sometimes try to avoid paying at all.
Plus points are, it's something on the CV/resume (but, be aware that employers more interested in your CV/resume than portfolio likely to be instinctively sceptical of any employment shorter than 6 months, and will employ few if any designers anyway) and you'll get good at fast working, keyboard shortcuts, workflow etc (assuming the experience doesn't put you off design work for life...).
Relevant book recommendation: How to be a graphic designer without losing your soul. Has lots of great practical tips about getting started.