While most newbies to spearfishing get seduced by the spear side of the equation, the first thing to sort out before you even think of guns and suchlike is your freediving gear... Which is not to say you can't get by with those old fins and mask that you have laying around the boat but if you actually want fish on the table your fins, mask and snorkel have as much to do with it as the gear on the sharp end.
long blade fins you might as well be fishing with a club! Long fins can be pricey so you might want to keep an eye out for last year's models or sales but whatever you pay, it will be well worth it.
The thing about long fins is they make you faster and get you where you want to go in a hurry with less effort (I was going to say flailing). With less effort you have more time on the bottom and with more time on the bottom you have a greater chance of catching dinner.
Freediving masks are, as a class, all low volume (spelled really really low volume) and you really need to look at quite a few to see what works for you... Personally, I shy away from masks in any color other than basic black and notions as purge valves and suchlike. As a general rule, masks are not cheap but I always seem to be able to find just the right mask for under $30... it just takes a bit of a search.
simple J sort in a soft material like rubber or silicone that you can fold over in your hand, otherwise you may find that a big fish + a rigid tube snorkel = expensive dental work when combined with a little Nantucket sleigh-ride action!
Getting to the sharp end next...