try arranging a "bar night" at one or more of your local bars that attract your target aged client el. As part of the evening, have a couple of guys, younger to equal the age of your target models, walk around and ask the guys to help out by being part of a video ad for your site. Many will be shy, but there will always be those who are just looking for an excuse to take off their shirt and smile for a camera! Best of all, IT'S FREE modeling. You could make arrangements with the bar owner to offer a free drink or two to anyone who participates. Play it right and you could have your ad done in a weekend and at the cost of a couple of bar tabs! PLEASE don't forget to take your model release forms and make sure that the bar has a fax machine or all in one printer that you can use to copy ID's or take your own!

This is just a suggestion from a humble marketer. Let me know what you end up doing and I hope you'll post a link on here to the finished product!