Ipa or isoprpyl alcohol is fairly cheap. you can get it in a pump spray from your local PC / hardware store at around 5 GBP / 7 bucks, about 300ml (good for 3 -4 cleans)
We just spray the full car and then let it drip dry. also another good thing to use is compressed air and or muck off. motoer cycle cleaner. i like ipa as it dries without leaving a residue. spray it on use compressed air (available in a can) to blow of any dirt. and then drip dry. Please make sure it is dry before starting up you enigne. IPa also does not harm electrics.