If you do buy a stock photo for a website, think about whether you want to use it in print. This requires planning out your strategy a bit, but can save you some money in the long run.
Stock photo houses typically price their photos according to the resolution that you purchase. They’ll offer a few different resolutions. These will vary from a small photo (3” x 4”) at a low resolution (72 DPI) for website use only at a low price up to large photos – full cover size at 8.5” x 11” at 300 DPI. Some stock photo houses offer even larger photos for trade show booths, posters or banners. But, the larger photos are usually more expensive than the smaller ones.
So, think about whether you’d plan to use your photos on future printed materials, and about the sizes that you might use them in. You can always scale a print-resolution photo down to use for your website, but you can’t take a low resolution photo and scale it up to use on a website without it getting blurry and losing quality. If you first buy a photo to use on a website, and later decide to use it on a printed piece, then most stock photo houses will require that you purchase the larger resolution – and they don’t offer a discount or credit for your previous purchase.