I would say the new heads are more of a priority. That's a nice kit you've got so you may as well get it to sound the way it should.
As for the pedals, check the local classifieds, craigslist, ebay, etc. for a good, used double pedal. BTW, I'll throw my vote in for the Pearl Eliminator for two reasons:
1) It's an awesome pedal and you can find one used for about $150-$200
2) It's one of the most adjustable pedals out there (if not the most adjustable), so for someone like yourself who is new to double-kick, you can make the necessary adjustments and set it so that it has the right feel for you. This is very important.
For both the heads and the pedal, it may cost you a bit more than $240 (depending on how many heads you need and how much $ you get the pedal for), but it's well worth it even if it costs you $300.
Hope that helps,
Mike