I don't know about price, but do you have the necessary wiring to handle an element that draws that much current? Most household wiring is only designed for appliances that draw up to 10 amps (2400W)-at least plug in appliances anyway. Hardwired things can be rated higher. I think you can sometimes get away with it as household wiring I think might be 16A but I really don't know but I don't think it's a wise thing to do. I'm sure someone else can pipe in with better knowledge.
Just something to look at if your not aware anyway.
That's why you wont find many people in Australia using more than 2400W elements. I get around this with my HLT by using two elements, one 2200W and one 1800W-I just make sure I plug them into different circuits so that there isn't more than a 10amp draw on a single circuit.
Cheers, JD