Average Cost for Installed SHW Drainback with 80g ?

Hi Daniel in Florida.  I am amazed at the cost of a SHW system these days.........4.5 to 8K, you say, with 6k being nominal?  I am doing hot water heating for 1/10th that cost.......Have about $600 invested in my system.  As I understand the technology, you have plumbed solar collectors on the roof, temperature sensors, water pump, heat exchanger tank, much pipe and wiring?  I am just thinking slightly outside the box here, and use an electric water heater with the lower heat element powered by an alternate electric source, which is a small wind turbine, but could also be a PV array.  Wind is cheaper than PV, and would cost me about 2K to do the same thing with a PV array of 4 panels at 48v.  I simply have more wind than sun in my midwest location.  The upper heating element is for quick heat, en-corporates a safety breaker, and usually a higher wattage than the lower heat element, which is for "cooking" the water.  I swapped out the lower element for a higher wattage one and supply it with alternative DC power, while the upper element runs off of AC as usual.  An electric water heater costs around $300 or less, depending where you buy it and is quite adaptable to alternative electric energy, and if it is powered by PV panels, then it technically is a solar hot water heater also.  The heating elements really don't care if they are supplied with AC or DC power, since it is simply IR heating.  My hot water supply is always toasty hot, and I have saved about 1/4th of my total previous electric consumption.  Sorry that couldn't answer your question, but I shared some thoughts....... perhaps others on this forum can help with that.  I wish you good fortune. :-)  Jon C.