It will, cost 8.000 gp.
The price of a weapon or armor is based on its total enhancement bonus, inclusive of all the powers.
If you are adding powers to an already enchanted weapon you pay the difference, i.e. upgrading a +1 weapon to a +1 flaming will cost 8.000-2.000= 6.000 gp.
Note that any magic weapon need at least a +1 enhancement bonus to the attack and damage bonus before they can get further enhancements of any kind. Armor need at least a +1 enhancement bonus to AC before receiving further powers.
if you want two +1 abilities, you're in need of first having a +1 weapon. (2000 + mwk + base [ + 2000 if cold iron ])
and then a +1 ability makes it a +2 equivalent weapon: +6000gp price difference. 8000gp + mwk + base if you're buying it all at once.
two +1 abilities rack up the price to a +3 weapon cost: 18000gp + mwk + base.