Howie’s addendum: The number of chairs I purchased for reception and each room was similar to Ho Sun. Since I was a startup I didn’t have chairs in my dilating room, about two years ago I added them as my practice got busier.
I found some used office furniture stores in my town. Google it for your town. I bought most of my refurbished used office furniture there. My office chairs only cost me about $30 each. I also bought some other furniture there, like a break room table, reception area table, large wooden desk for my office (it’s beautiful but in retrospect I wish I had bought something more contemporary and lightweight) and a filing cabinet.
It cost me approximately $2200 in used furniture purchases to outfit my 1500 sq ft office. Note that this would only buy three chairs at the price that Ho Sun’s architect quoted above at $650 a pop. Five years later everything is still in good shape.
Other companies that folks have used for chairs and furniture include Overstock, Wayfair, and this link: http://bertolinichurchchairs.com/products/liberty-115-hybrid-church-chair-indigo-black/
One important point, if you have a hard date that your office will be ready, you could simply order items and wait for them to be shipped directly to your office (rather than put them in storage or your house) so you don’t break your back and your wallet moving. Frequently when you buy from a shop they will hold and store it for you until your desired delivery date. If you’re ordering online, place the order a week before you get the keys to the office.