I don't think you'll need to fund it. If you haven't read the PDF of his complaint, the listing of facts is surprisingly strong.
Seriously, it is short, just read the few pages in the middle. Complaint in PDF.
The claims include that there are written documents (probably email) between the mayor and the chief of police, where the mayor tells the cops to do something, the police chief says there is no legal basis, and the mayor tells him to do it anyway. Then the claims include that the cops made written statements (again, probably email) that show officers were ordered to arrest him, they balked saying there was no legal basis, but the police chief ordered it anyway. If he has those emails, that is rather damning.
The list of claims continues by citing court records, where the police filed an empty form citing no probable cause even though the law requires proper documentation. Granting a warrant based on a blank probable cause statement is also pretty damning for those involved.
If he actually has those papers, city officials and court officials declaring that they knew it was illegal but did it anyway, that is going to be hard for the individuals to deny.
A few of them are likely just CYA papers, but if accurate, the exchange boils down to this: "Do this illegal thing." "Sorry boss, it is against the law." "I know it is against the law, do it anyway." If the allegations can be substantiated (and since the suit says those are all public official records, it should be easy to validate) then this case will be a quick settlement.