Replacement foam trimming for front/rear hatch

Where can one find replacement foam for the front/rear hatchs? Online or local retail?

I have an older kayak, an Aquaterra Prism, the foam around/under the front and rear hatches are shot. I flipped once in the bay and my kayak took on some water. I noticed that it didn't feel quite right on the way back in. When I tried to lift my kayak, with a knee strap used as shoulder strap, I noticed the kayak was quite heavy and it shouldn't be. So I opened the front hatch and there was quite a bit of water inside the hull.

Being a newbe, I know that flipping will happend once in a while. So I would rather be repared then have the yak sink on me.

The prism was the first yak I ever paddled, I didn't flip and still got a ton of water in the hatch from water over the bow.  I went to Outback Adventure in san jose and they said they have a basic rubber replacement strip you can buy and glue on yourself.  I never replaced it though. 

Thanks brah, I'll checc em out.