How to find one? https://www.google.com/search?q=patent%20attorney
Expect to spend ~$10k (lawyer + patent filing fees).
That being said: if you don't have resources to defend a patent (read: hundreds of thousands if not millions of dollars in lawyer fees, months-to-years litigation) then don't bother getting a patent.
also, many (most?) firms will charge a flat rate for certain services (e.g., drafting and filing) or a capped hourly rate (e.g., $250/hr but no more than $3000). something to keep in mind if an attorney insists on an uncapped hourly rate (which, i hope, would be rare).
[edit: after filing attorneys will also charge for responding/arguing with the patent office. this part ('prosecution') usually varies firm to firm but often is very similar (e.g., a set fee for each type of response, which there should only be a few of)]
patents.google.com is a good place to start.
Patents help you get acquired and get investment. But, they are very expensive to defend.