There are tons of options on Amazon - I've used three of them - red, blue and purple. I chose ones that would wash out after 4-6 weeks.
The colour was gone by the end of three weeks - that was my only disappointment. Otherwise, they were loads of fun, and I did it myself.
I would warn you to NOT rinse your hair out in a white bathroom hahahaha ... I learned that fast (and the hard way). If you do it yourself (it's not hard at all), rinse your hair in the kitchen sink. I had to scrub red dye off my white bathtub - it came off easy enough, but not something I had anticipated on doing!