This can be a very subjective answer. Everyone will have a personal favorite, but most people tend to lean towards the gear that their instructor uses or recommends.
This answer also can depend on the actual equipment involved. I have personal favorite brand for my regulators, but that brand does not make the particular type of BCD that i prefer.
Research is your best bet. Talk with as many long time Scuba divers as you can, and make sure their equipment is suitable for the environment you will be diving, ie: cold water vs. warm water regulators
TUSA has contracts and purchases from the same factories as major brand name equipment but at blue label prices. Good quality / price mix.
There is a store called Scuba Dive that sells equipment and gear in Ocean City
If you are not certified No you cannot rent scuba gear
A scuba compressor can be found at Leisure Pro, Amazon, or Best Scuba Gear. If you need to save money and don't mind purchasing used equipment, Craigslist and Kijiji regularly have compressors available.
You you either need a bathysphere or "scuba" equipment.
I spend about $3000 UDS on my initial set of scuba gear that was all very high end equipment. Others enter scuba with rental gear that can be returned after each trip or dive. It is a good ida to have your own gear if you plan to dive a lot or go professional.
The best area to sell scuba gear in the USA is to set up scuba gear shops in areas near bays and oceans. This could mean on the USA's three major coastlines and also the many large lakes that exist in so many places in the US. The Great Lakes is an excellent place to sell scuba gear.
I did not myself, but friends of mine did. SCUBA equipment had been around for many years, and was used by Navy personnel from time to time.
Equipment changes depending on the location of the dive and purpose. Basic equipment include, wetsuit, fins, snorkel and mask, lead weight, scuba tank, BCD (Buoyancy Compensation Device), and Regulator.
Different scuba gear types weigh different amounts. The oxygen tank is the heavy part of the scuba diving gear.
Scuba was invented by the navy.
The website titled the best scuba dive gear has a lot of good information on scuba gear in general. They have a section describing the various types of dive lights and which is best in different situations.