From Personal experience, I say don't do it.
In my first business 6 years ago (an MLM) I invested over $1500 in products that were difficult to move and I spent about $1000 a month in buying leads. It was a lesson learned.
Long story short. If I were starting all over again with very little money, I would start with free advertising like free classifieds, blogging, article writing, squidoo etc. and then I would roll the profits back into my business until I could start doing some paid advertising like pay per click.
The only thing worth investing in would be personal development products that would help to teach me the skills that I need or perhaps a proven system to help me be successful. For example 2 years ago I invested in Mike Dillard's Magnetic Sponsoring. Because I wanted to learn how to "attract Prospects" rather than buy leads. It was a great investment.
Make sense? So I would only invest in personal development and do free marketing until I gained the skills to be successful.
I hope this helps.
What do you think? Borrowing from your credit card a good investment or bad move?