I currently have an 250 power supply ( PSU) but I am going to change to an 450 Watt PSU . If i do will I get higher bills .

The PSU capacity doesn’t really make much of a difference. The bigger PSU might use a little more residual energy for cooling, etc but ultimately it all depends on how much wattage your hardware requires. You might want to ask yourself if you even need the bigger PSU. If you know someone with a UPS that displays power usage, ask if you can hook up your system to it and get a reading. I have 2 servers with multiple HDDs, etc both with 870W PSUs here in my office and they are collectively drawing 180W. I was shocked!