even if the spraying must be done by professionals, and therefore is more costly than other options, the high R-value of spray insulation can make it cost- effective over time, through lower heating bills. In very cold or hot climates this advantage may be well worth the cost.
Spray insulation also carries the advantage of filling uneven areas well. The sprayed foam expands to fill cracks and fit into irregular spaces that would be difficult to work around with other kinds of insulation.