Estimating costs for various jobs

[Da Deep]

I'm going to look at a new house that's not finished. The basic structure is up but drywalling and interior is yet to commence. The builder is open to selling AS-IS or after completely finishing or in-between.

What's my best option? Should I have the builder finish the house to my choice of material? Should I buy AS-IS, then get it done myself by a 3rd party? What tools/sites can i use to assess what the interior will cost me? kitchen/flooring/fixtures/etc?

TIA, Dave