Hi Mike, Congratulations on your OW and welcome aboard!
Choosing a dive shop has a lot to do with location.
I've found reasonable prices and have had good experiences
with a number of places -- such as See in Sea (kakaako),
Aaron's (Kailua), SSA (waikiki), Surf n Sea (haleiwa),
and a place in Aiea that I can't remember the name of.
But like other things, your mileage may vary.
Mail order is OK but postage is high.
Another alternative is to look for used gear in the Sunday paper.
Lots of bargains can be found there.
Don't forget fishing supply places for knives, gloves, etc
and places like McCully Bike Shop often have different choices
for masks, booties and stuff.