Bring lots of money to any of a thousand prototyping design shops. There are any number of small shops with staff that can do that kind of prototyping and pre-production work. $50-100K can get something like that going. The digital part can be done with FPGA chips like Xilinx without the expense of custom ASIC chips that would be the solution for volume production. For a product that only needs hardware available in a smart phone, just get somebody to write an Android App for it. Plenty of those development shops around as well. I could recommend a few in the San Diego area. But if you're looking for HDMI inputs as well as others, you might just want to prototype it in a micro PC first or a single-board computer.
If you have a unique idea, better to spend the money to patent protect it first.
If you're not looking to sell it as a product, and don't care about size, look into the hardware available in carputers.
Can you give any more details?
If you're on a strict budget and don't mind subsidizing some learning and failures along the way, you might contact local college EE professors if they need student project ideas.