Negotiating Wages

I was just reading on another site about a travel company who has nurses negotiate wages. As I have not yet gotten so far as this, I wonder is it customary to try to set your own wage? How much can you affect your overall pay when bargaining with companies? Will companies try to undersell first time travellers or are wages lower on first assignments because hospitals prefer nurses with travel experience? Thanks muchly.

No, yes, and yes respectively. First time unproven travelers represent a risk for all involved. Risk comes with cost, so yes, agencies compensate for that increased cost with lower pay - or a crappy assignment that is high risk anyway.