I guess it will depend on your particular insurance policy and more importantly how much your deductible is ?
If it's just a leak that is drain pipe involved my guess would be somewhere around $150 for plumbing and drywall repair (plumber may well have to cut an access hole to get to the pipes)
If it's a faucet leak, the cost would climb depending on just what and how the faucets needed repair.
Insurance usually pays for "damage done" not repair of. Repairs are part of home maintenance, again though your particular policy might have an allowance for water leaks, so a quick call to your agent or insurance co. would be a great place to start.