It costs money to order, pickup, warehouse, deliver, or stock materials. I don't think 30% covers the cost.
I'd think that on really big items,(over $1K) a 10% or 20% markup covers the costs but on coverplates, switches, breakers, etc. 100% is certainly fair, 200% wouldn't phase me.
I'm the maintenance supervisor for a city school district. I have to account for all of my costs. I have to figure out what it costs to have one of my guys drive to the electrical supplier to pick up a ballast we don't stock. The real costs are outrageous. There are lots of little jobs where the hidden costs of the job are larger than the man hours and materials costs. If you generally charge 30% markup, you're loosing money on materials.
I hire a lot of contractors. I know their costs of materials because I probably buy more electrical materials than most of the contractor's do. On big projects, I expect to get materials at close to cost. But on little jobs, 200% markup on a little part seems more than fair for a guy who just dropped everything to drive an hour to solve my problem so I can open school at 7:00am.
On rare occasions, I've been given invoices with 400% markups for materials on little jobs. I'll remind the contractor that I shop at the same supplier he shops at but on small jobs, it's still not big money so I don't really balk too much.
[This message has been edited by maintenanceguy (edited 11-14-2004).]