It'll be difficult to buy a VR Headset directly from a shop in Sri Lanka, most probably computer parts sellers will say "they can place an order for you and you'll have to pay & wait until device comes".
Even though VR headsets available in Sri Lanka, they will be so expensive since they cost more than $500 even in US, so all the taxes and SL shops charges definitely increase the price over Rs 100000/150000.
Since you don't want to experiment or develop vr games, don't go for a OSVR HDK.