How did Bitcoinica get its prices? I'm interested in building a Bitcoinica replacement and wondered how did they get their pricing information.

Was it from Mt.Gox and was it verifiable, I mean could you have gone to a web site and seen a history of prices and therefore know why your position may have been liquidated ?
As far as I know: 


Yes, Bitcoinica's prices were based on MtGox ticker
Using the MtGox price, they had an algorithm to build their spread (you will always buy on bitcoinica at a higher price and sell at a lower price than the reference mtgox price, thats where a broker like bitcoinica makes profits).
Yes, Bitcoinica had some charts, where you could see the reference price, and the spread (the graph was called "daily quotes"), so yes you were able to check the price and spread and understand why you had been liquidated.


No guarantee on these answers, I'm not in the Bitcoinica code, this is just how I understand this.