For the 'serious' collector of almost anything, three things are essential - cash, patience, and a willigness to learn. If you're collecting Rembrandt's, you'll need more cash than anything else for the one that may become available in your lifetime.
Fortunately, for crotons, you need more patience than cash - and not a lot of that unless you're looking for that one that no one else has. ..and with patience you'll need some persistence. Most of us built our collections a few plants at a time over several years or more. I've found that most members and especially some on this board have been quite generous with cutting and air layers. I'd never have some of the varities I have without some generous folks like John Bender.
So hang in there, go to meetings and meet other collectors who share their plants and especially their knowledge.