now that i think about it maybe i should just get the backdrop and take pictures outside

I'm assuming you meant taking photo's outside without any lighting

Taking photo's outside with a backdrop would be hard to control, indoors with lighting that you increase/decrease is more ideal, you wouldn't be able to get different effects that would look good.... how many outdoor studio's have you heard about? there are location shoots but even then it's more than often with lighting too.

Do you have any photo editing software, like Photoshop? If so, you could save money on backdrops, and just shoot on a green screen, then add whatever backdrop you wanted digitally. It would be more convenient as well, since you could leave the green screen up, instead of going through 'x' number of backdrops. Just a thought.