Well, it's not so necessarily about money as about how inconvenient it is to have a scoped shotgun vs. how inconvenient it is to have a shotgun without scope.
I bought the shotgun for its versatility, i.e. to be able to hunt deer, rabbit, maybe some birds down the road. I believe that a scope on a smoothbore when rabbit hunting might be a nuisance (at best), an obstacle or safety hazard (I heard lots of stories about getting a black eye from the scope and don't want to experience it).
I don't intend to shoot a deer at distances greater than 100 yrds or so (or I would purchase a rifle for deer hunting and then I would install a scope). Hopefully, I shall be sufficiently good at that distance for a lung area.
However, if there's a scope which can be mounted and useful for quick target aquisition (to do rabbit/birds shooting) and safe, I'd probably strongly consider such option... My eyes aren't perfect even with contacts.