I bought Lennox high efficiency furnace (94% efficiency) and Air Condition in Toronto in the end of Jan. 2009. The list price was $8300, but the company knock out $1,000 for the business (my furnace broke down then, so there was no time for shopping around).
I will be able to get $1000 allowance for furnace (500 from fed and 500 from Ontario); $400 for AC (200+200) after the second evaluation; plus 15% on $6300=$945 for the tax deduction next year; and the following rebates have been received already:
$550 rebate from Hydro Ontario, $165 from Enbridge;
So the net cost for both Furnace and AC is
7300-(1400+550+165+945)=7300-3060=$4,240 .
Since installed in the end of Jan., my gas bill saved over $100 each month for Feb. and Mar.
This was the case in the Toronto area. LZ may shop around to get a good deal. Good luck!