Hi David,
I had a couple of very similar situations recently. Small phone no. to add on to fascia, web address etc.
1st one- I had the vinyl, but the job was over 1hr away, so I had to recoup what I’d lost in fuel. I charged my standard rate + travel. To the client this had no justification when you think about just one small line of text and he left it.
2nd one- Locally, but I didn’t have the vinyl. I bit the bullet and ordered the material, done the job as an add-on service, costs/profit ratio for the vinyl/time used were bad, but you know, the client was happy and hey, this might bring on a job based on his recommendation. It is always good to keep a working relationship and provide sort of after care, then your advertising cost might improve because of word of mouth from satisfied customers?
Sorry to drag on 🙂
edit:
sometimes I bugger my other local sign makers for a bit of vinyl 😳 when I’m desperate… They do help out – I would as well.