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.
I dont reckon you can beat the old belle kettle element myself. $10 from bigw and you've got 2400W on tap. enough for a HLT anyway. If you need more just add a second element and find another power circuit to hook into.
If your lucky enough to have a 15AMP outlet, get an electrician to upgrade it to a 20 AMP outlet. It will probably just mean the outlet be replaced and a bigger fuse / CB fitted.
At the moment kirem, i can bring 30 L to the boil from tap water temp in about 1hr 15min. I am planning on building a bigger HLT soon using the same element. I suspect it wont be able to bring 45 L to the boil but should be ok getting to HLT temps. If boiling is what your after you may need 2 elements. I'll keep you posted when i get around to setting it up.
My HLT holds 130 ltrs I use a 2400 watt element controlled by a thermostat. I also have
a backup 1800 watt element that I can manually switch in and out this is on a different circuit . I do not have any problems with incorrect temps on brew day.