Price for legal help with a visa

Hi. I am about to apply for the visa de objeto determinado. Onfortunately, I am already here on the 90-day tourist visa. I have two questions: Will I have to leave the country on my tourist visa and then re-enter with the visa de objeto determinado?

After getting the visa de objeto determinado, I am thinking of hiring a lawyer to help with the rest of the process, as I work and don't have a ton of time to devote to it. How much have people payed for lawyers to help with this process? I speak Spanish, so I can work with someone who doesn't speak English. Thanks for any advice!