Cheap tires with free shipping?

I need a set of tires for my 94 suburban. i need all for matching for my 4WD. however, I only have 500 to spend and i need an allignment as well. I might be able to get them mounted for free. are there any sites where I can get a new set of all terrain tires for around 400 with free or cheap shipping possibly? id like 245/75/16 or 225/75/16 tires.