Thanks everyone for the ideas. Something to think about, but I'm still leaning to making my own suits.
Ideas so far are, adapting a some copyright free court cards and just changing the suits.
Blue: star, crown
Green: maple leaf, cross
I gave Russell (Sprouts) a suggestion that will save a lot of hassle if he takes it and uses it on his deck design. I'll offer you the same advice, adapted to your design.
You want to create new suits, check.
You're still planning on having the old suits, am I right?
Take an existing, in-print USPC deck design, such as Bicycle Standard or Bee Diamond Back. You could even try Tally Ho, but I wouldn't range out further than that - stuff like the Hoyle Shellback, Aristocrats, etc. don't get reprinted much and the first two are exceptionally common, found all over the country.
Now, instead of recreating your own courts and spot cards for the four "original" suits, make your back design MATCH that pre-existing deck, so that by combining that deck with all or part of your new deck (consisting of only the new suits), you can create a new deck with as many as eight suits! You can even match the courts of the traditional suits to your suits, giving your deck two suicide Kings, four one-eyed Jacks, two bedpost Queens, etc. Now you've gone from having to make a 104-card deck (not counting jokers or extras) to only having to make 52 - you can sell them in sets with a standard USPC deck that matches your deck's back design, and even provide an oversized box that holds the two decks together, in tucks or loose. That can be key to getting a deck like yours accepted by more people - the design will be so ridiculously familiar, you'll have people willing to give it a shot just for the hell of it.
Even better - you have the option of selling just the new deck suits. The old deck suits are crazy-easy to find, so if someone wants to save a few bucks (and save you the trouble of warehousing twice as many decks) you can offer the new cards as a separate product, like an "expansion pack" for the existing decks! Even outside the card collecting community, there's hardly a household in this country that doesn't have at least one of those two super-common decks.
Now, the most critical part: keep the new suits INSANELY BASIC AND SIMPLE. Star, fine. Cross, OK. Crown and Maple Leaf - people will starting thinking your new game is Canadian! How about Circle and Square, or perhaps even Circle and Triangle? Uber-simple, easy to identify, easier to distinguish from the other suits at a glance.
I have a friend who does graphic design for a living, print and web. He told me about a company that wanted him to create a logo for them. Initially they complained that his designs were too simple, too basic, didn't say enough about the company, had no words in it, blah blah blah. So he created a presentation for them - he grabbed the logos of several of the biggest companies in the country if not the world, sneaking his design for the new logo among all those of the multi-billion dollar firms. It showed these executives that a simple, clean, streamlined design was simple - but simple is what works for logos. Their logo that he created for them blended right in with the "big shots" as if it belonged there. They ended up using his design in the end.
I think you see where I'm going with this - if logos should be basic and simple, card suits should be even MORE basic and MORE simple, especially if you want them to be as widely accepted as you can make them. Simple shapes work best.
