I wouldn't specify 'median' exactly. That sounds too technical - it doesn't have the same innocence and emotional appeal. I'd mention what other local companies are hiring for the same position at, and mention being surprised they aren't offering at least that. Or mention having friends that got hired for the same position at a salary that's 10k more than you're being offered. If you do it smoothly, I think the worst case scenario should be that they say they can't go any higher, or that they come back with a higher offer that's only 1/2 or 1/4 more than what you mentioned. Like Sun Tzu said, don't corner the enemy.
