Could it be because I mail them just that, a list of prices, and then say something like: "Um... please look at my website for pictures and then spend some time matching those up to prices, because... um, I just can't be bothered to do that for you because I'm, like, making things"? Yep, I think that might be it. Not that that's quite how bluntly I put it, but oh - the arrogance! And laziness! And total terror of line sheets.
Here's help: indie retail academy's post about line sheets. So you can go from this:
(I know there are people who enjoy doing this sort of thing, and I'm not one of them. It's a bit like cooking: I don't like doing it, but if I have to it might as well be done properly. There's satisfaction in performing the final copy-paste, there really is.)
(Oh, and if you do do this, you might lose another day or two making really spiffy order forms in Excel, with sensible stock codes and very satisfying formulae that slot into place so neatly.... You'll be glad you did, and even gladder when it's done.)