Hmmmm, please accept my apologies Richard.
At the end of the day, data is a commodity, information (ie processed data) is very expensive. If you need it, you're gonna have to pay for it (ie it's ultimately going to come out of your p/l).
Bear in mind however that you're also gonna be dependent on your in-house market data team to maintain a stable environment for you, find out if they have they set something like this up before (this sort of thing is an art not a science!).
May I ask what markets your looking at? (equities at a guess from the prime brokerage reference?)
Setting up a new desk is always going to incur fixed costs, min number of peeps to cover holidays etc, however sharing trade input screens for example shouldn't (on a "this is a greenfields operation so we need to monitor costs" basis) be too onerous.