That depends on how many rooms, the number of fixtures, whether the home in question is a two story or single story home, access issues for wiring, and the age of the home. If this is a single story home, the installation of canned or recessed lighting is a great deal easier than if the home is a two story unit. There can be serious access issues with a two story home, and this might require a lot of holes to be made in the drywall to fish line through the rooms. Also, depending on the age of the home, the electrical loads will increase for the canned lights, so older homes may require a new panel to be installed if there is not sufficient breakers for the added electrical load.
However, assuming that you have a one-story home with adequate breakers and a newer electrical panel, the cost for installation of most "retrofit" canned lights is about $80-90 per light with the fixture costing between $40-50 each. You'll also need dimmer switches for each room, so add another $10 per light swtich.
Grace Morioka, SRES, e-Pro
Area Pro Realty