My driver side ball joints need replacing. A shop I took it to quoted me $450 bucks for labor and parts plus a lifetime warranty for parts and labor.
Is 450 reasonable?

 

Is that for both ball joints on the drivers side? 900 is extortion to change out ball joints on both sides...

You can easily get those changed out at home with basic hand-tools and a rented ball joint press.

The hard parts are busting the axle nuts off (get them loosened up at a tire shop if you don't have air tools), getting the bolts out of the wheel hub/bearing assembly, and getting the hub out of the steering knuckle.

All of those issues can be mitigated with the right technique. For example, using a socket extension, you can use the hydraulic pressure of your power steering to push the wheel bearing/hub out of the knuckle with minimal effort.

Tools needed ;
Hand tools (Sockets, wrenches, screwdrivers, etc)
Big scary hammer
Extra Cotter pins
Ball joint press from Autozone or O'Reillys
Dictionary/thesaurus (to invent a few swear words)

My advice (if you can turn a wrench) is to take a weekend and do it yourself at home. For the money you save, you could literally rebuild the front driveline yourself for less than the shop is charging you to change the ball joints on one side.

Check YouTube for some videos, there are a few that are pretty inclusive

Edit: only use SPICER/DANA ball joints as well. The cheap ones from the parts store just don't last. Rock Auto and Amazon usually have the cheapest prices from experience

 

Go to several different shops for an estimate on replacing all the ball joints that sounds high and try a few 4x4 shops and alignment shops to boot.