Looks like nice original 18K Seamaster- case looks reasonable for 18K, this ref has no bezel if you look at side views, movement looks clean with proper movement- if you like the reference looks like clean original example to me- and 1500 not unreasonable given gold value. If they can provide proof of service and some kind of warranty even better, fair to ask if it is being sold as recently serviced.
Crown looks original too.