I bought mine (#472 with just under 13K miles) over a year ago for $65K. At that time - just before Model S trade-ins started, it was a very good price. Now, I think it is a little high for a 2008.
There were some great deals a while back when Tesla dumped a bunch of CPOs onto the market - but I think that prices for what you are describing are in the $55-60K range now and will continue to drop a little each month for a while just like normal used cars.