Thank you all very much for your comments! The house plan we chose comes with a standard gas fireplace as an included feature. Mystery Machine, correct, the house will not be a walkout, and the cost to upgrade it to an indoor/outdoor gas fireplace is about $5500. And nkereina, your comments regarding outside venting (of the standard model) are spot on - the builder warned us about that. I guess to me, $5500 seemed a little pricey considering a standard gas fireplace is included. The comments about being cheaper during the build process (rather than later) are duly noted. Everything seems so expensive, that I think I have a case of sticker shock lol.
We do live in the Charlottesville, Virginia area - in case that matters. The Cost of living is on the higher end of the spectrum.
And heatherc and dopeydame, thank you for the votes of confidence.