Can't sew - have to buy - how to compare?

[Kilted KT]

1. For the same weight, yds, and tartan hand stitched I find the costs range from a high end at about $720 + shipping to a more affordable $404 including shipping(with X Marks discount). Can there be a $300+ difference in quality in the final product from reputable stores? What?

Honestly, you can find that much of a difference, but most of the people who notice those differences are usually kiltmakers. One of the big differences is if the kilt is hand sewn or machine stiched. The difference in quality here will have to addressed by someone else, as I don't have a fully hand-swen tank yet.

5. Cost has me leaning toward Scotweb especially in light of the discount and the free shipping. But how does the quality compare to the more expensive kiltmakers?

Don't forget that while it may have free shipping, you may have to pay import taxes or other such fees.
for a similar price, check out http://scottishkilts.net/ Some of their tartan kilts cost less than the ones on scotweb.

6. I have read about duty charges from kilts received from outside the US that I would like to avoid. Anyone have experience with these charges on kilts coming from Scotweb? It seems to have to do with the shipping carrier.

see above...

I realize I have a lot of questions but this seems the best place to learn. Thanks for taking time to read this long post. Hope you can help.

Cheers! Bill

you are definitly in the right place to learn about kilts...I am confident you will not come up with a question that someone here can't answer.