There are several Canadian sites with nic-base up to 65mg/ml (highest allowed by law, though one or two places may still be selling 100mg/ml). I like FusionFlavours.ca for nic, flavours and glass bottles (for rebottling for longer term freezer storage) but dashvapes has better pricing on litres of PG and VG.
You'll get more help in the DIY subforum for flavors/recipes and such --- I
vape a lot of unflavored, or lightly flavored (tobaccos and menthol) liquids, so I won't be much help with a piña colada mix.