Like everyone else said, 7lbs is a good weight. Paying $2,000 is a little steep, but if you live in NYC, Yorkies are going to cost more than usual, regardless of their size. The average going rate around here is something like $800, but a good deal are listed for $1,200. So, you weren't ripped off as badly as it might seem, due to the average cost of Yorkies in your area. I hope that makes you feel a little better!
I paid $500 for my newest Yorkie, but he isn't registered. His parents were 3lbs and 3.5lbs and he's tiny himself, so it was a really good deal. Smaller Yorkies are sooooo exspensive around here, $1,200 and up. My second youngest Yorkie is AKC and champion sired and I got her for $550, but I think that was because I was young and cute and wanted a puppy.

I think I payed $500 for the oldest. As for their weights, puppy is 3lbs (4 1/2 months), Maddie is 18lbs (but should weigh 12lbs) and Puppster is... 30lbs?? The weigh can vary a lot from dog to dog, even from the same litter.
Congrats on your baby!