Little point in getting a Sata-111 if you only have Sata-11 unless of course its cheaper as they are backwards compatible. But yes I agree prices are dropping but if you always waited to see if prices would fall any lower then you would never buy anything.
I have at the moment a Crucial M4 128GB and I rated highly,I have an OCZ in the past which not quite a highly rated. Sandisk I probably would not buy but would be happy with the Kingston.
But there are plenty of reviews out there so have a look around and also take into consideration what warranty you get.