Hawknballs, what you're looking for are called stock photography sites. It's where news outlets and such get those ambiguous images you see in every newscast.http://tomuse.com/stock-photo-sites-buy-sell-images/
Getty Images is Seattle-based, so if you find some good ones on there to buy, buy from them since you're supporting locals. Plenty of stock photography sites don't seem to have sports images, though; likely due to NFL licensing rules...
You could go to http://images.google.com
and do a search for "Seahawks", or something similar; then click the Search Tools button on top, and click Any Size, then go to Larger Than and select 2 megapixels or 4 megapixels; that way, you only are looking at really large photos suitable for printing.