I'm left eye dominant as well as left handed.
I'm right handed, and right eye dominant, and I shoot both right and left handed, give it one range trip and you'll have it figured out
Or go with a Stag lefty from Arms East
People can still shoot em (the lefty Stag's) right handed, the modern AR was designed as an ambidextrous rifle, with the case deflector, charging handle, and easy ability to add selectors.
If you want that specific stock, its about 400 bucks for the magpul UBR, however a Magpul CTR (about 100-150 depending on where you get it) is a very nice stock.
You can get rail systems anywhere from 150 for the cheaper ones (UTG or yankee hill machine) up to 300+ for top end ones like Daniel Defense and Troy specialty ones. Fabsports has a 9" (midlength) free float troy for 199 on their website, a regular carbine length (6") would be a little less probably.
A flip up or fixed rear iron sight, depending on if you want optics.