Before hiring a lawyer, I would recommend looking into things on your own.
For starters, you need to establish if this 'family in Canada' can sponsor you or whoever you're asking for. What is the relation between the 'family' and the one you want to see sponsored?
Read hear about who can sponsor:
http://www.cic.gc.ca/english/immigrate/sponsor/relatives-apply-who.aspIf the person you're sponsoring is a child or spouse, go here:
http://www.cic.gc.ca/english/immigrate/sponsor/spouse.aspYes, of course you can use a lawyer to do this for you. But there's really not too much more to it than filling out forms and waiting. And waiting. And then waiting some more. Personally, I don't think you or anyone needs a lawyer unless there are some complications, like if the sponsored person has a criminal conviction or a custody battle or whatever.
The cost of hiring a lawyer really depends on a lot of things. How good the lawyer is and how much time they would spend on your case - most charge per hour, so if you have a complicated case and they have a lot to do, you could be paying a lot of money. I would suggest contacting some and asking about their prices. Then you can compare and see what would work for you.