If you pay for printing costs you should be marking the cost up 5–10% to cover your associated labor, costs, the risk you take of losing the money if the client doesn’t like the final product, and the time your money is tied on the line while you wait for the client to pay you back. If the client doesn’t want to pay your markup, you give them the files on CD and tell them to deal with printing themselves.

Advertising agencies routinely mark up all purchased goods and services 17.65%; however, if you pay the printer in order to charge the mark-up, you're on the hook if your client is a slow pay or no-pay.

some of it depend on what kind of designer you wish to be. good designers or agencies can nickel and dime their clients. While medium and low end have to think about soaking up the costs to be price competitive.

You can also negotiate a flat consulting fee for print management. You and your client may both prefer this, since you won't be penalized financially if you reduce their printing costs.

I would keep time & expenses entirely separate. If you need to spend time picking a printer, getting printing bids, doing a press check, etc then there's no reason to hide that in your markup. It's a legitimate part of your design fee.

Expenses such as printing should be itemized separately on your invoice, and it's customary to add a markup (in the ballpark of 15% is fairly common). And always mention the markup in your estimate ("a standard markup of x% will be added to all expenses") so there are no misunderstandings later.

Often the markup is justified because the designer gets a trade discount from the printer and then can charge retail. The client can't really complain about the markup because they'd end up paying the same either way.

> Often the markup is justified because
> the designer gets a trade discount...
> The client can't really complain

Yes, but as long as the markup is reasonable, there's no reason for a designer to ever feel the need to "justify" adding a markup. Adding a markup is standard business practice. Every plumber, carpenter, painter, optician, ad agency -- virtually anyone in any business -- adds a markup to their expenses.