As Baldy says, Bud's gun shop is a good one to deal with. Just be advised that they will tack their merchant fee (3%) onto your bill if you use a credit card.
CDNN is also a good one
http://www.cdnninvestments.com/
These guys get TONS of police trade ins. You cannot buy firearms from them online, you have to call in your order. They have a huge calalog available for download
http://www.cdnninvestments.com/dowournewcat.html, but handgun prices are only available over the phone.
And just to clarify (since no one has done so yet), when you buy a firearm online, it ship to your FFL, who you see in person to fill out the standard paperwork just as you would if were buying the gun directly from them. Face to face transfer--with its attendant background check--is required.
Secondarily, buying this way means that the cost of shipping applies. A gun shop will have their bulk shipping costs built into their prices, buying a single gun to have sent to you means that this higher, one-off charge is yours to bear.
Always look at total delivered cost, and beware of those who may inflate their shipping charges after they lure you with a low unit price.
And did I mention that the gun ships to your FFL? Don't think that the guy in the brown truck is going to knock on your door and hand you a gun...it don't happen that way.