Beauty is in the eye of the be(er)holder. The 60/61s are rather unique in their styling- some people like them, some don't. Personally, I like them!
Having "unique styling" can limit your field of potential customers. Fewer customers = less demand = lower price
You might consider researching eBay listing history of 60/61s to see how the prices compare to their conditions.
My opinion: 60/61s tend to command lower prices the other series
Bill