IGA in Spiceland Mall is a reasonable place to get standard wines on Grenada...
http://www.realvalueiga.comIn the same Mall is North South Wines...
http://www.northsouthwines.com/ I haven't been to North South so can't comment on prices so I suggest you contact them and ask.
I imagine it is possible to ship wine but, again, haven't done it. What I have done is ship boat parts and I can tell you getting them cleared through customs was not a lot of fun!