So my wife took my Volvo to the shop to get things maintained and when she got back i had a huge crack in my headlight lens. I found a place that I can purchase just the lens with clips and gasket. Question is should I buy the whole assembly or is it going to be easier to replace just the lens? The assembly is like $300ish and lens is $130.

 

Buy just the Lens.
But you have to pretty much remove the front bumper cover to replace it.

 

Ouch....

 

But it isn't really all that hard.
Search the instruction have been posted about removing it to replace the light.