Usually you pay a bail bondsman a percentage of the total bail. In CA it's 10% unless a lawyer sends you with his card then it's 8%. You do not ever under any circumstances get this money back. This is the price of assuming the risk that the defendant will not show.
Other forms of personal bail include putting your house up to guarantee appearance. This usually happens where the bail is very large. If the defendant skips you lose your house.
Should I bail him out?
That depends. Of course he wants out as soon as possible. But there are programs that will get him out for no bail (depending on the crime) and some of these programs must spend a week or two in evaluating the case. If that is your situation I say leave him in. If you pay the bail premium you are paying a large amount of money for a week or two out of custody if the program accepts him. If they don't accept him, you can always bail him out when he's been refused.
An important consideration is how you are going to fund the defense of the case. Say bail is $300,000 and you have an attorney so you can spring your loved one for $24,000, leaving you almost nothing to pay the attorney. Have you helped the defendant? Not really especially if you don't qualify for the public defender. Better to take the bail money and buy the best defense possible.