In reply to cb_6:
New jobs are like relationships, it's easy to think "oh my god I really need this one" but you might find something better will turn up. Stick to your guns and keep your dignity, if they weren't willing to pay you a decent wage is this really the crowd you want to be in with? Why wont they at least match (in real terms) you current salary? Are they struggling as a business? Are they so short sighted that they'd rather employ someone on the cheap rather than reap the benefits of employing the right person for a bit more? What's the rest of the staff moral going to be like if everyone's thinking they should be paid more?
You did the right thing imo, as long as you were polite then asking for more money and supplying good, well evidenced reasons should make any decent employer
more interested, not less.