Most inventor assistance services are designed to separate you from your money. You should rather: 1. Research whether your idea is unique or new 2. Create detailed plans and a model of your invention 3. Visit a reputable patent lawyer in your area and seek advice and a patent search 4. Save up some money you're going to need it to create the working prototype you'll need to begin exploring ways to bring it to market.
I have known some people who have had success aproaching companies that produce similar products and pitching to them before completing any of the above steps. 1 person made a deal for a long term employment contract with a company. Another sold the company his idea and they never brought it to market. If you go this route, make sure you have plenty of documentation (photos, plans, etc.) to prove the product originated with you, and be careful. Otherwise, i'd pay a couple hundred to sit for 20 mins with an experienced lawyer and get their take before I started cashing in my 401 K.