Stock photography, istockphoto?

I found a few stock photography sites. I am starting a cosmetic line and I need a very simple flower picture that will be used on my website, labels on my product, and on the outside packaging. Some of the stock photo sites seem too good to be true. If I spent $10 or so on an image...what gives? Is it not exclusively mine? Is that the catch? Or can I not use it on labels but only on my webpage? Anyone familiar with the legal systems of these sites?

Stock photography, istockphoto?
I found a nice site at http://simsphotography.bravehost.com/ where everything is a dollar and you have direct communication with the photographer so if whatever you want isn't up, you can request it. I had to request one of the scenery photos and he took so many similar ones I had to buy most of them! Good thing is it doesn't cost more than a dollar depending on how hard it was to get/make, in fact everything is a dollar so far. Plus you can request galleries and save some money instead of buying one by one. I was very happy with there customer service and I will continue using that site. Hope this helps!
Reply:A good site should explain what you're getting for the money. I would think that $10 will only allow you to use a low resolution image on your website.

If you want exclusivity then stock photography is not the answer, anyone can pay the fee and use the same photograph.

You say that you need a simple flower picture, I presume that you mean a photo, what did you have in mind? I'd be happy to take a photo for you, or sell you one I already have, with exclusive use.

Search for my ID on Flickr for examples of my work.