Kakaku.com's store listing are the smaller, non-chain types. A quick glance shows most stores only accept 代金引換 (cash on delivery) or 銀行振込 (bank transfer) for delivery orders. This might create complications with hotel as third party in the transaction.
I have done this in the past, using kakaku.com to do price research, but purchased the camera at a physical store in Akihabara that sells it at the same price as their web site/kakaku.com. Look at the "在庫・発送の目安" (in stock, shipping) column for "店頭同価" (same price in store), and "地域" (region) column for "東京" (Tokyo). Check the store web site for directions to the stores. Also, it will be easier to inquire if they can do 免税 (menzei, tax exemption) in person, as the merchant will need to see your passport and staple the form into it. Not all stores can process tax exemption.
Bait and switch or grey market goods should not be a problem, but check over the model number and warranty certificate, which should bear the store's chop, just in case.