Used monitor under$600 with good bass low levels

It would make much more sense to design from scratch just buy the drivers that Bolzano use and copy the dimensions as closely as possible (drivers are usually around $50 each) - DIY clones are common enough (more common for classics though). Nevertheless the whole thing will take skill and you will probably need to experiment to get the right sound. I'd build something simpler to start with though.

I can't imagine what you will do - in my minds eye I see two used monitors strung together with hockey sticks, duct tape and bungee cords?

I plan on consulting with Meniscus, they have been in the business for a long time. I will let them help choose the drivers and design the cross-over and other parts.

Now you are talking - glad to hear you are getting some help - this is no easy slam dunk - for sure!

If speakers were designed and played back suspended there would be a consistency that the designer will know will be heard through out

I have used these Omnimount to suspend speakers. They have various models for weights up to 300 LBS - they are used in clubs and stage. They work well. Nothing wrong with suspending speakers - it is a great idea if they weigh a lot and you have toddlers..