The housing generally does not allow heat to dissipate as well as non-IC lights, so lower wattage bulbs will have to be used.
Recessed Light Cover
If insulation is present, it may still be possible to use non-IC lights, but they will be more expensive to install because the insulation will need a baffle to hold it back at least 3 inches from the light fixtures. This not only costs money to install, but it also reduces the effectiveness of the insulation, meaning an increase in energy costs.
Costs vary greatly by region (and even by zip code). To get free estimates from local contractors, please indicate yours.