Need advice on SWCG purchase

[Jeffski]

We decided to go with a Salt Water Chlorine Generator for our pool that is being built now. The walls are up, liner in and full of water, backfill and cement coming this week.

The cost of the SWCG was not included in our quote because I didn't know about it at the time. Now I am wondering how much it should cost and what type of unit I need. I like to be educated and not just take the builder's advice (especially since he didn't recommend the SWCG...see other posts).

My pool is the basic liner 18 x 36, about 3.5 feet in the shallow and 8 feet in the deep. I don't know how many gallons that is.

So what brand, power, style, etc should I be getting and how much should it cost me?

Thanks in advance, you guys/gals are great!

PS My pump and filter are made by Pentair if that helps.