I think people are crazy not to have it and should see it as a cost of running your business. Your lifestyle is based around your ability to earn. That income should be insured. As you are self employed, any State benefits are means tested.
If you are unable to work due to accident, illness or injury, you will be paid a replacement salary until you return to work or reach retirement age.
Cost wise, it's more expensive than the other benefits due to the higher risk of a payout and the long term payouts (if you went on a claim, they could potential pay out for 26 years).
Price is determined by level of cover, deferred period (when it starts paying out. You can have a pay out after 4 weeks or as long as 52 weeks), your occupation (office based are low risk, on sites are high risk), the chosen retirement age.
While there are 5 providers in the Irish market, not all plans are equal, so cheapest isn't always best.
Steven
http://www.bluewaterfp.ie (www.bluewaterfp.ie)