Question about RAM

My PC currently has 3 sticks of Corsair 2048MB 1333MHz DDR3 ram. I wanted to upgrade this to 8GB but not sure how to find a compatible 2GB stick and an affordable one at that. Can someone please help me here

Cheap, low profile, and to your exact specifications.

do they not make your RAM anymore?

I've found these 3:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820145246

http://www.newegg.com/Product/Product.aspx?Item=N82E16820145331

http://www.amazon.com/Corsair-2x2GB-Desktop-Memory-CMV4GX3M2A1333C9/dp/B002TISFCG/ref=sr_1_4?ie=UTF8&qid=1385971665&sr=8-4&keywords=corsair+1333+2Gb

I hope any of these will fit.