A run of the mill US patent is about $12K.
Local machine shops are your friends: you can submit the drawings for bids. A number will do assembly, including PCBs and wiring up to the packaging point.
You want to find people who will proof-read the drawings, clearly explain the material choices, and commit to a scheduled delivery.
I have an interest in a local machine shop and the above is pretty common.
Courtesy * Integrity * Perseverance * Indominable Spirit * and Self Control
Tenets of TKD