Even if you believe hiring a professional is the only way forward for you, I would suggest you read plenty of information regarding the accessibility of records in El Salvador and any other country you think your ancestors may have come from, to get a handle on whether this research going back so far is even possible and/or what you might reasonably expect someone to achieve. You could begin by reading the articles here:
https://www.thefhguide.com/project-9-central-amer.html
Such a project could take a very long time. I would not trust anyone willing to place a figure on such a project at the start, as there are so may unknowns.
Many people prefer to study their ancestry themselves, as this is much more fulfilling than hiring someone else to do it for them and for most the cost of using a professional would put the project out of reach. Many on this site are at least as competent as many professionals, but I doubt there is anyone here who has experence in tracing ancestors in Central America, if that is where you ancestry lies.