I'd say it's a mistake to not charge a mark up on your materials, although I assume you're not doing that from what you've already said. There's nothing intrinsically ruthless about applying a fair mark up. If you think about it re-selling materials you purchase for a job at cost translates into you making a loss on every single item you buy, and subsequently resell as an artefact you've made. The reason for this is that it requires your expertise, time and effort to establish your material costs for a job, the right materials, that is, not inappropriate ones, and frequently using your own vehicle (and time) to collect some or all of those materials.
In my own business, largely moribund now because I'm over retirement age and can longer be much bothered chasing work, I have the following mark ups.
- Rough sawn solid wood which I then have to true up (saw, plane, etc): mark up = 100%
- Board materials, e.g., plywood, MDF, etc: mark up = 50%
- Proprietary items, e.g., polish, hardware, anything I basically just open and use: mark up = 20%
- Finally, after pricing up all of a job's materials I add 10% to that total to cover sundries such as abrasive papers, screws, nails, adhesives, all the sort of stuff kept in stock but not usually allocated to a specific project.
So, as examples, if I were to purchase rough sawn black walnut boards at £1000.00 they are automatically resold to the client at £2000.00.
Similarly, £1000.00 worth of 2440 X 1220 X 18 mm plywood is resold to the client at £1,500.00.
As an aside, my estimates/quotes only show to the client a final price for a job after giving a description of the project and the materials to be used, that sort of thing. Materials are listed in my estimate/quote and I can see the various sub-totals, but they're hidden from the client's view by the accountancy software I use and the way I've set it up to generate estimates or quotes.
It's not greedy or ruthless on the maker's part as far as I'm concerned to mark up your purchased materials for a job, and nor are you obliged or duty bound to tell your customers what your mark up is. I'd go further and say that it's none of your customer's business how much you mark up your materials, and if they ask for that information I'd politely (usually) decline to provide it. Better still, perhaps is to consider running away from the job because that's a sign of a potentially difficult client who'll refuse to pay you fully at the end. Slainte.