If i were to purchase an Iphone 3G in my home country with vodafone would it work with a vodafone sim bought in another country...??

Good question, I think you better ask at your local Vodafone. I got my iphone from Vodafone as well and they promised it would work anywhere abroad as there was no sim-lock and they also told me many ppl jus bought the iphones for export. I've tested it abroad and it worked just fine.