Don't know about sexy rexy but for the best prices on beer go to the beverage wholesale place called Top Choice on the roundabout. It was around 19 usd last time I bought one but not sure about recent price increases (b sure to save your empties & return them in the plastic case for deposit).

Rum drinks are anywhere from $5 up (in my experience) and RS you can find as cheap as 150J on the beach ( try Cheap Thrill Corner/patty shack between SeaSplash & Treehouse they have cheap RS & good patties).