Why not ask one or more. But beware, I`ve heard many stories of `invention development` companies that will take your bucks and do little or nothing. Find one that has experience in the product and market area you are working in. Be sure to ask for references and call them. Make sure the reference isn`t an employee of the development firm posing as someone else. If these firms want your business, they will give you some assurances. Make sure you pay as milestones are achieved, not all up front. Better yet, give some cash along the way and a small percentage of your profits ongoing, if they`ll go for it.
Sorry to be negative, but I hate inexperienced people getting taken advantage of.
Best of Success to You!