Just echoing what many here have already said.
I go mainly for the food items. Part of the fun is finding suprises "Look they have "xxxxxxxxxx" I haven't had that since the 1990's".
I also appreciate the warehouse design, which means Wiiiiiide aisles that you can maneuver around in (Anyone else notice that supermarkets here have narrow aisles and Dominicans are not shy about blocking the aisle w/ their cart as they shop? Then when they see they've blocked you they're in no hurry to move unless you ask them to?).
PriceSmart imports some good fruits that you don't always find in other Supermarkets.
Big family so we buy in bulk and it works out great. I know poorer familys that go in on a membership, will buy things like rice, beans, diapers, in bulk, then split them up at home. I find the membership price here expensive. Other PriceSmart franchises in other Latin countries charge less than half of this membership price (Equivalent of RD $350.) I suspect they charge so much here to keep the riff-raff out?
Hit and miss on prices. I don't bother checking on electrodomestics much. I found a 32" Plasma TV/DVD player once for US $700 equivalant, other than that I can almost always find electronics and eletrodomestics cheaper. El Canal btw, is a great find! They don't do a lot of advertising but they're definitely a place everyone should be familiar with. Again PriceSmart....one item is 25% cheaper than anywhere else in the country and the item next to it is 10% more expensive than La Sirena or El Canal. Pick 'n' choose.
As another poster mentioned baby formula and diapers (Been a few years now since I had to purchase them) were MUCH cheaper than anywhere else.
I also like their fast food. Their 10 piece bucket of fried chicken (Best in the country IMO)is $380 (?), their 18" New York style pizzas are a very good and a great bargain at RD $380 and their hot dogs with the steamed buns, onions/relish wheel are awesome if you eat that stuff.