Notwithstandng the valid caveats above, prices seem to be a bit higher for lawyers than Immigration Consultants. For the lawyers, about $4000 is middle of the range. For consultants, about $3000 seems average.
What they all share is the desire to get you to pay up front and only THEN will you know whether they are good, and whether you can work in sinc.
I might (were I starting over) look for a consultant familiar with the country of the applicant, who has the experience and contacts to help you get things like translations and notarizations in that country. That type of help can be invaluable. If a consultant says that they don't need to know the applicants's country to help with the forms, then you will be spending hours looking for translators and notaries online.
I would hire him or her JUST to help with the forms, giving you a chance to evaluate his expertise, and only then determine whether to hire him for the remainder of the process. Get a contract that spells out the specific serices to be provided -- including preparing a document checklist (identifying documents not necessarily specified by the Immigration document checklists). Vague promises like "help with the application forms" is not sufficient.
I will go it alone from here on in. Not one consultant was able to give me a direct answer about what they did to "represent" me with Immigration. If Immigration calls for something, all the consultant does is forward the request for me, and chek on status periodically , which you can do yourself.
