Got oxymoron? As Barrie said, you get what you pay for, I've stopped buying those cheap aqua-one heaters and only buy Jagers now because the aquaones are inaccurate and don't last. When you're considering the price difference between heaters, consider the cost of the livestock in your tank.
Also, it might be a bit overkill on a 165L tank, but could be worth while if you've got some expensive fish, two smaller heaters are better than one bigger one, gives you some sort of backup if one dies.