I'd still get the bids just to compare. Sometimes a fabricator has a bunch of beam lying around, and can get really competitive. It's really just about the economics, unless, as Bruce has pointed out, the property aesthetics and utilization preclude anything but a monopole. I'm assuming, since you threw out the I-Beam idea, this unit is on undeveloped ground. Even then, you need to think about the long term effects. Why do you need the huge "V" to begin with? If the sign has a very short read in one direction, you may be better served building a one-sided sign.