i'm not a techie but I've been working in banks ever since graduating 5+ years ago.

Perhaps not the story you want to hear - I've never negotiated for any pay packages but for different reasons, at different stages of my working life.

At the beginning, I was one of those that kept preaching about "experience over money".. and partly because I have low expectations to begin with + I was really a timid person. I just took whatever that was given to me for as long the scope is one that interests me.
Later, my moves were mainly through headhunters who handled the negotiation for me / direct recommendations from someone up there, so its fairly straightforward - $X or I walk.

Looking back, i felt i could've done better when i was just out hunting for jobs. Honestly,for as long you approach the topic in a professional manner, I don't any sane employers will retract the offer just because you try to negotiate...though I can't speak the same for SME...

That said, before attempting to negotiate, please do your own due diligence on the market rates. And that includes corroborating the figures on the market reports.. those figures tend to be overstated in most cases...