Hi -- If your kitchen base & wall units are in a good clean condition / state of repair and securely fixed and you do not plan to change the layout only update and give it a new fresh look, then it's a lot cheaper to just renew the cupboard and drawer fronts along with the worktop and fittings if required.
The fronts are easily replaced just take your time doing one at once until you've lined up the closing action correctly, the bit where you may need professional help is the replacement of the worktops and fitting / cutting of new sink and appliances etc. After you have done this no-one could reallly tell the difference whether the whole kitchen has been replaced, after all the chipboard faced carcasses are just that.....chipboard.