have 50$ spare and a socket too..!!

so gonna buy a RAM DDR3..

Please guide me to the best ram possible under the price tag...
I have G.skill 4Gb DDR3



already installed...
See my system specs for details...
i have a HP-Dv6 also can i change its RAM ..?? it has 4Gb-DDR3 too..
any suggestions..??!!!?? Suppose a Gaming RAM..
Thanx.,.,.,.,
BTW anything else i can spend my cash on!!