Tough call.
I would go in to whatever shop isnt full of bike shop D*ckheads and tell them what you want (assuming you know).
Say: "look, I can buy this surly LHT (or whatever) online for Xx dollars, but Id rather support you guys. How close to that deal can you get? I understand you have overhead costs too..."
If they want to make the sale, they'll be straight with you- They may not be able to match the offer of performance online, but if they can get close, and they are good guys, support your locals. This is my motto even though I dont need them for anything (mechanical, parts, tools etc.)
That said, in a shop full of d*cks, I tell them they just lost a sale. Had to do that the other day to a dude giving me attitude about spokes I needed to buy (telling me I couldnt do what I wanted to do, and had done before)... Went to the onLineBS, ordered exactly what i needed, got it a few days later for less money and no attitude, built the wheel.
I dont support LBS' as a charity case, they have to deserve to exist. Unfortunately many don't meet this criteria to an able cyclist and mechanic.