The WH-205 can be picked up cheaply on fleabay, and while they're fairly respectable in themselves (if your phone / device works with them that is) the real value IMO are the clear silicone sleeves they ship with. They have a noticeably higher overlap towards the back of the sleeve than regular Sony EX-style eartips and offer more isolation, and are compatible with earphones I've tried from Sony, Sennheiser, JVC and more.

I've found these for a very cheap price but i bought the CX-300 V1s when they 1st came out and wasn't impressed by the lack of the bass in them. Have they changed anything in them for more bass like the MX range I was very happy with the MX500s and the MX660 i had up to the point where the bass actually starts to pop back and breaks. It will be either theses or the MX760s as these are now cheap as well Thanks