water high pressure cleaner

There are so many in the market - trust, mikachi, pacific, bosch, and of course karcher. Can you tell me, which one will be a good buy? Don't want to buy an expensive one if a 3000 - 4000 range will work as good. Need one to wash car and the house roofs (also to clean the blackened walls). Checked Price Guru. Karcher 110 bar K2 is 5100; whereas, mikachi 190 bars is only 3850 :( . Afraid of "bon marché coute cher."