pleaded non guilty were smart. I am basing my comments on the info Jas provided. Since no sex took place and no exchange of money it is difficult to prove the "crime."  

The best strategy in the hobby is to verify. However if you were stupid and did get arrested, keep your mouth shut. Cops have to prove you guilty and that takes time and effort and money. Not sure if there would be interested in taking you to court. They are in the game to quickly close cases.

Now if a verified hobbyist or provider has been flipped and you get caught, then you are in deep shit. Any suggestions on how to get out of that situation?

A couple of things; first, Illinois does not recognize a plea of "no contest"  You either plead guilty or not guilty.

Additionally, it is impossible that a plea of guilty to a misdemeanor prostitution would yield a fine and costs of 5K.  The maximum fine on a misdemeanor is $2500.00 and there is no way court costs would add another $2500.00  More likely, in Cook County and particularly in Chicago, fines and court costs on a finding of guilt would only amount to several hundred dollars.  

Also, if your friend paid a lawyer 5K to negotiate a guilty plea involving extensive fines on a first court date she truly did get f!!!!d!  Moreover, no judge has the power to order someone to not return to town.  Maybe in an old western but not in this day and age.  

In these matters, often times the wiser course of action is to set the matter for trial and call the bluff of state.  If ultimately there is a finding of guilt, first time offenders are eligible for, and very often receive supervision which is expungable.  Finally, it is unlikely a first time, misdemeanor prostitution offender is looking at jail time after a finding of guilt.

So while it is important to always exercise wisdom in the manner in which we conduct business, it is also important to get accurate information on what is, in the scheme of things, a pretty minor arrest.