It’s a bit of hard one to answer, two ways to look at it.
We primarily work with vehicle graphics, so for us the largest cost is wages, and overheads, so my main concern is the time element of the job.
I know what it costs to keep the place running, if it’s costing me £30 an hour to keep the door open, it’s no good spending 5 hours on a £100 job.
Similarly if you’re printing a mug or a t-shirt. The mug costs £1, add a bit of paper and the ink, and you think you can sell it for £4 – Until you account for the time involved.
If you can turn your item into a commodity/product item, and get the volume you can look at it differently.
If you know you’re making £5 on each order, and it costs £2000 a month to keep the business running (and paying your wage), you need 400 orders or 100 a week or 20 a day, to break even.
Increase your price by £5 you then only need 200, 50 a week, 10 a day.
Are those numbers achievable? How do they compare with the competition? *Also remember you don’t want to be working 5 days a week, 52 weeks of the year.
I know a few people who’ve successfully grown their business, by standardising some items, and offering set prices. To do it accurately you need to know your costs though. 👍