I bought FM years ago and never learned it; the learning curve was too steep. Then I got Bento and things went great (fun & easy to use) until I hit the wall: Bento ran out of capabilities for what I needed to do.
So I bought FM Pro 10. Too late for either of us to get an upgrade discount, by the way.
FM Pro is *not* fun - and is a major investment in learning. But it can do just about anything.
Probably the best deal for you would be a pre-made solution, if you can find one suited for your business.
DonorTracker is absolutely right.
And if you can not find a pre-made solution in FileMaker, then I suggest that you use Bento to create your Portfolio only and spend the difference in a good accounting package for your invoicing and book keeping. Otherwise you will end up spending more time in front of your computer rather than behind your camera!
So do you or anyone know of a reasonable price, preferably free, pre-made solution?
This one comes free with a new FMP 10 license or if you download the 30 day FMP 10 trial version:
And this one is at the other end of the scale:
(I don't know how well these fit your requirements.)
Probably you have already tried this, but why not also ask in a photography forum? Best I know is is on dpreview.com, such as The Pro Digital one at:
Other forums to try would be Open Talk, Mac Talk or one of the camera specific forums.