Howdy Sam,
First of all, the Doc Holiday rig does come in .38/.358 even though the website doesn't show that. But it is still expensive. You can buy the .357 gun alone in standard finish or nickle, wood grips or the Tru-Ivory grips. And they also carry this gun made by Pietta, in standard finish or polished stainless. The "Thunderer" grips on the Pietta version are slightly thinner. As to your final question, yes you can buy a Ruger but if you buy a standard Ruger you will need to get a Ruger birdshead gripframe for it in order to mount the birdshead grips in your link. I'm not sure if Ruger currently sells the short-barrelled model with birdshead grips already mounted.