Unless you're fortunate to be in an NPC station where you have standings, you'll get hit by the 5% unavoidably, but it's the price you pay for being able to move 35 bs's worth of minerals out to 0.0 in a single carrier jump.
Financing this is all another matter. Don't assume the corp wallet can pay for everyone's battleships - we simply can't afford it without a steady income, which means that we'll have to work together to do it through all these methods we've been discussing elsewhere.
Right now though we've not even considered the size of the problem: how many bs's do we actually need, who actually wants one and is going to need to have one built at the base location, wherever it may be. All details we can thrash out in due course.