Replacement Window for Condo/Townhome

I live in Northern NJ and recently starting getting prices on replacing 8 single hung windows (replacing with double hung), 1 sliding glass door and a basement window.

Quote 1:
Trustguard windows - $6500 (charged me $60 extra for Low E Argon on windows and $120 for door)

Quote 2:
American Thermal by Crystal - $5200

Quote3:
Okna 500 Series $5900

I am still waiting for 1 more quote, I believe he said they were Viking windows.

Are those prices good? I was expecting to spent around $3500. My friend did his whole house (25 windows) for $11k.

Those prices are definitely within the range of reason. In fact, they really are not even that far off from your friend (although he is on the lower end), given that you have a patio door in there. The Okna option is hands down the best choice that you've looked at. It is one of the nicest products available, IMO... You could conceivably get a far better value than your friend if you choose that product and he bought an inferior choice.
There are a couple pros here that serve NJ as well, anthony and masterext. Not only would you get a great product, but peace of mind in knowing that you are dealing with a great company as well. I believe that they serve different areas of NJ so you'd have to click their "Get a Quote" buttons to see which serves you.

N NJ would be masterext.

He would take very good care of you.

Mastertext for sure.

What do you know about Alside windows?

It is probably the most commonly reviewed window on this site. A search would yield a bunch of info... IMO, they have a product line that ranges from bad to average (I cite the performance ratings as evidence). Most of their lines are very bulky, leak air, and have pocket sill designs which are undesirable. I've seen a fair amount of issues with quality control as well. If there is one bright spot, their customer service has always been good in my experience.
Ultimately, I'd just reiterate that your Okna quote is very reasonable on a product that is by far better than the others you've seen.