Brand purple shampoo vs DIY

There are several points to consider when deciding what to use to tone the hair

1) price- good pigmented shampoos can be expensive. I like Redken silvercharge shampoo as it is very pigmented but it sets me back £14 per bottle. Others have good results with provoke which is much cheaper but it doesnt do much for my hair.
2)brassiness- is your hair pale yellow or orange? with conditioner/dye mixes, it is easy to change the ratio and make them darker or lighter depending on the level of toning needed; as well as using wither blue or purple dye.
3)how long you want to leave it on- shampoo can dry out the hair, so i wouldnt recommend leaving it on more than 30 minutes. the dye/conditioner can be left on overnight (if needed)
4) consistency- shampoo color is more consistent per batch as you arent mixing it with anything so if it worked well, then its easier to achieve the same results over an over when doing the roots.

I found this deal at TK Maxx which sell Goldwell Dual Senses Blondes & Highlights Anti-Brassiness 1L5 for £15 and which is very cheap compared to actual price. I also look up the product and it seems to get good reviews.

My hair is rather yellow and not orange. I wonder if I needed more purple in my diy shampoo or it is just not working for me. However as the deal for brand purple shampoo is quite good, I'm considering buying a proper one.

I don't leave the shampoo on for very long. Just 2-3 mins. May be I should left them on for longer?

I think you will have better results with an actual hair dye than food colouring.

Also having this dilemma! I'm in Canada though and I always have more difficulty finding shampoo/conditioner here than I did in England.
I made a conditioner toner with cone free conditioner and directions violet dye. It really toned out some green I had in my hair but didn't do much for the gold blonde bits I had. Only tried it once though and left on for around 20 minutes.

I'm forever faithful to Bonacure silver shampoo for toning my hair, or pro:voke touch of silver for a cheaper option, though lots of ladies on here have had great success with making there own toners from semi dyes and conditioner.