Will salons charge less for toner if I bring my own toner with me?

They might charge less, but not much less. It's more about the time than the cost of product. Cost of product will be cheaper to them anyway, buying in bulk means discounts.

For one of my professional keratin appointments, I brought along my Touch of Silver shampoo and asked him to use it before my treatment.  He had no problem with that, and I wasn't charged any more or any less.

For one of my professional keratin appointments, I brought along my Touch of Silver shampoo and asked him to use it before my treatment.  He had no problem with that, and I wasn't charged any more or any less.

That's very different though. It takes no extra time to use a toning shampoo. Using a toner with a developer takes extra time.

They will probably subtract roughly the amount they pay for product, or they may subtract the retail price. I agree though, they charge more for the time than the product itself. Salons get things a lot cheaper than the consumer does. Like here in the states, salons usually charge double what they pay for a product or more. Like a $20 bottle of conditioner cost them about $8-$10.

You'd be best ringing and asking. We were a L'oreal salon and the staf trained to use L'oreal products, as a result some didn't feel confident using other brands they weren't used to using. It is kind of like going in blind.
They might be happy to do it but may not want to take responsibilty for the final colour result, if it is a somewhat unknown to them.

Is charging for toner a common thing? I pay £55. This is for full-head highlights, shampoo/conditioner/toner, a nice head massage & a blowdry. I didn't realise some places charge for toning aswell :o.