Hey,
Try websnapr.com. They had a pretty neat looking tool and it got most of the websites I tried in less than 30 seconds. They have varying levels of pricing, but they do have a free license that lets you get 100K thumbs in a month. Your site does not look like it would exceed that so I would say that is your plan. Requires no software download or install on your part and to get the images to appear on your page could be done with javascript, your existing form, and a div + img to catch the thumbnail.
Too easy :-) You want me to set it up for you? The project bid is up there. Otherwise I would take the milestone payment as a donation to my cause, heh.
Regards,
Matthew Olson, MS