iKlear
I just use distilled water, but occasionally use 50% isopropanol made from pure isopropanol diluted with distilled water.
I would not recommend ethanol because most ethanol is denatured which has all kinds of additives in it to prevent drinking, which may not be ideal for cleaning purposes. Pure undenautred ethanol is too expensive due to liquor taxes.
Ruahrc
Too expensive - 227ml iKlear costs £20, whereas 1000ml isopropanol costs £10! And ethanol i can siphon off at school...
What does iKlear actually contain?