If the tractor has been well cared for and kept under cover that is a very good price for all that equipment. Not a bad price really for the TLB alone much less the bonus implements.
I doubt it is a CK20S however, more likely a CK20 as the S version did not come out until 2007 as I recall. Not a big deal, just one less horsepower and a few other changes, no deal breakers. I loved my 2004 CK20 TLB.
As I recall the major issues with these are 1) is the HST pedal sticky from rust if left outside, 2) is there any evidence of leakage at the BH valves, 3) does the key switch work properly (again vulnerable to rain). The biggist issue however is the loader. I presume based on the 2005 model year that you are looking at a KL120 loader. These are very good and powerful loaders but they have a distinct tendency to develop cracks in the corners of the cutout on the torque tube. Take a socket set with you to remove the cover (10 minutes) and look in the corners. There is a retrofit kit to control this cracking and it may have already been installed (if not I'm pretty sure Kioti would arrange to get you one for no charge). None of these loaders has "failed" but lots of them have cracks (probably most). Some people are very upset by the cracks while others are content that there is no loss of function and that the retrofit kit stablizes the situation.
Check to see that the loader and BH and tractor have been properly lubed. There should have been a few oil changes and one HST oil change with filters so I'd check on that too. A 2005 should have the suspension seat, if it doesn't it is really a left over 2004 (no changes I recall except the suspension seat which you definitely want).
The equipment you are looking at would total close to or above $20K new so 13K for a set up with 150hrs on it seems like an excellent deal to me.
