I'm now printing everything in grayscale for several years. For outside labels placed on the cover, I use bright yellow paper instead, which is more eye catching than the yellow print had been anyway.
What a good idea. I wonder if that would save me money. Thanks.
The "problem" is that there aren't any affordable self-adhesive yellow inkjet/laser labels on the market. I couldn't find anything else but expensive brands in small packages, going for about 0.50 up to 1 € per A4 sheet. For comparison: I pay about 7 € for a 100-pack of white self-adhesive labels in A4 (good quality).
However, using the self-adhesive inkjet labels on the outside of the books turned out not so much of a good idea anyway: They seem to attract dirt. If such a book is haunting the boxes and shelves for a while, the labels often look just filthy.
So I resigned to using the yellow standard paper (non-sticky), cutting them myself, and fixing the paper pieces with strips of transparent adhesive foil. My outside labels are rather small, no more than 65x35 mm but usually less, so a standard 50mm (2") wide parcel tape roll does the job. Price tags: 9 € for a 500-pack of A4 paper in intense yellow (cheaper brands I tried came with poor printing results), 2 € for a 66m/50mm roll of tape.
My supplier for the latter two is a local family-owned office market mostly known for high-end office furniture - people often have a hard time to believe me that this shop often sells better quality for less money than the nation-wide chains, online shops or even Aldi and Lidl... really, they rather suggest that I must have miscalculated the price per sheet than accepting that envelopes or labels at Aldi are simply overpriced ;)