You may want to check out http://fritzing.org/
You can design projects in here, and send off to get a board made up once you've set you files up.
A couple things..
First, I couldn't get the 'send PCB' link to work when I messed about it a while ago.
Although it may work for you?
I tend to use Proteus, but that also costs quite a bit!
Searching for 'free PCB design software' should bring up a few results.
Make sure they have capability to footprint SMD and that you can design your own, or you may be stuck with using DIP and through hole components..
If you are going at this to make money, it may be worth investing the money in pro software in the long run, or, get your project protected, and then look for someone to back you finacially, then you can buy what ever you need!
Another option would be to learn to etch boards yourself, search for "PCB etching, toner transfer method".
This would be useful to test your boards out before you send them off to manufacture.
You may want to consider where you've placed your display, what if a ball hits it, or it gets damaged in transit. (Just a suggestion.).
Watch out for licencing pitfalls, eg the safety of yor product if you wish to release it commercially and if there are any other products that have protection on your design that you may need to adjust or change.
Best bet would be to see a consultant and talk to them about your idea (make sure you get them to sign a confidentiality agreement!).
Also, think packaging, website, branding, promotion, marketing.
All essential in a good business plan..
Hope this is of help, and all the best of luck with your product!