Costco.com has the DynaTrap Insect Trap 1/2 acre coverage for 69.99. Free shipping: Costco.com [costco.com]
I got it from my local Costco for the same price, and it came with two replacement bulbs, I would think online does as well. This is the cheapest I've seen for a 1/2 acre trap since I started looking for one a couple of months ago, and price history shows cheapest in past year was around $80.
Amazon seller currently has it at $97.99: Amazon.com [amazon.com]