You want the C1 version for the 60D, rather than the C3. The C3 has the wrong cable for your camera. The $90 price is what I said about being quirky - it is not what they are selling for. Look at the prices they sold for under the xxx sold and you will see prices like $30.45 and $29.55. Make him an "Best Offer" of $29.55 or so and see what they answer back. Tell them you want free shipping also - they offer that on the C3 version. Tell them you are also buying the YN-468 II. They reply pretty quickly, usually within a day. If they won't work with you on the C1 version, there are other options. I bought my second set of two off Amazon for about the same price.
The cable provided with the RF-603s is only used if you want remote shutter control. For remote flash, put one RF-603 into the hotshoe and the other with your flash at the desired location. Put flash in Manual mode and shoot away. You will not get E-TTL with the YN-468 II using off-camera flash. Only the more expensive flashes have that capability. For off-camera flash you will probably be better off with manual control anyways. I already have a Yongnuo YN-460 II which is totally manual and works well. Going for the YN-468 II for times when I could use E-TTL on camera. But also want to be able to use two off-camera flashes. Considered the more expensive YN-565 and YN-568, but don't want an on-camera flash that is any bigger than the YN-460.