Usual reminder that you don't need mini, and that if you really want some, a cheap alternative is to print images on poker-token (that you can buy for a ridiculously low price on Ali Express)

As usual when talking about 3D printing, look for a fablab near you. While individual printing will be more expensive, it includes the rent and maintenance of the machine, and gives you access to a wide variety of machine to match your specific needs. IMO, unless you plan to be a heavy 3D printer user, the fixed cost of even a cheap machine won't offset the extra cost of going to a fablab, having access to high quality machine, and a local community of enthusiasts

You want someone with a resin printer over a fdm one. You will get waaaay better quality.

For a standard mini I would assume the material cost to be less than £1.

Expect it to be a chunk more than that as it's the cost of the printer/staff/shipping that will make up most of the amount.

This is probably a better question for the 3d printing communities.