The original 510 was made by Joye. All the others are knockoffs. Many of the imitators work fine but they shouldn't be MORE expensive than the original. You can get a starter kit (2 batteries, 2 atomizers, charger & some pre-filled carts) for $35 + shipping. If someone is charging much more or trying to get you to sign up for regular shipments of pre-filled carts, do not buy from them.
BW, Jaunty & DSE are major e-cigarette manufacturers. Their quality control should be similar to Joye's. Yeti is just altsmoke's name for their 510. Other places have named theirs as well (Totally Wicked = Titan, etc.)
There are a lot of good things about the 510 including how adaptable it is. The bad thing is the battery life. If you are one of those people who will vape for 15 minutes after meals and that's all, you won't mind. If you live in the real world, consider something with a longer-life battery.
Fortunately, you can get a 510 with a much better battery. It's called an eGo. I went straight from the standard batteries to a battery mod (I love my Little Chuck) so others would have to advise you about the eGo.
Adaptablility - in addition to the variety of ways to power a 510, you can use it with carts. The filler material isn't perfect and you will find yourself looking at cart mods on the forum (I liked the straw mod and HighPing's one.)
You can drip in a 510. No filler needed -- just add liquid directly onto your atomizer and vape. I like this for some of my liquids. You have to add liquid more often than with a cart, but there's no waste and its very easy.
You can get cartomizers for your 510. They are like the cartomizers for the V4L or the KR808 except larger. They hold almost 1 ml of liquid. If you get the ones with the soft, removable end pieces and replace it with a drip tip, refilling the cartomizer is very easy as well. I love the cartos for the 510.
Whatever you decide to start with, welcome to vaping.