I assume you mean the Webley Mk I service revolver; if not, ignore the following.
If it is the early Mk I with the holster guide and recoil shield made as part of the frame, they have been going for around $800 in very nice (90%+) condition. Later Mk I's bring less.
(BTW, many of those old Webleys were converted to use .45 ACP with clips by turning down the backs of the cylinders; they are worth much less and should never be fired with factory .45 ACP, which is much too high pressure and has burst some cylinders, even on the Mk VI.)
Jim
