Dying hair highlights (level 8) to level 5 question?

Hi- I have natural level 5 roots according to Sallys- so i got this color and peroxide to match. My hair is shoulder length and is a level 8 blonde from many highlights and sunshine. Q- I want to avoid block colour as this looks like lego hair on me! Can I drag out some of the expensive blonde bits, foil them up and then dye my hair as usual, with these peaking through? I'm thinking Katie Holmes with long hair at the Valkerie premiere. Otherwise, a cameron diaz style brown. What do you think? OR i can dye all over and get highlights put in at a salon. (I have a free voucher for half hed of highlights- but all over dye was going to be an extra �30/$60 so I'm, trying to save a bit of cash.)