I've been going to Sam Flax for about 20 years now. Yes, they are a bit pricey, but if you need something right now, they usually have it. Staff is generally friendly and knowledgeable, with one exception...
Stay the hell away from the framing department, It is not run by Sam Flax. The space is rented by a total jerk who has pretentious slackers working for him.
They refused to cut mats on sale in Sam Flax. WTF? He says his mats are hand cut. Total BS. They are cut on an automatic, computer controlled machine. Offered a dollar a cut for 20 mats - $120.00 for about 15 min of work. He still said no, I had to buy the mats from him, at his ridiculous markup. When I mentioned he wouldn't cut Sam Flax mats at checkout, the cashier said, ""Do I have to talk to him ...AGAIN?""
Bought 20 sheets of matboard, which will give me 40 mats, and a nice cutter for half of what he wanted for 20.