We put up a GSI bin very similar to what you are thinking about. It was $80,000 for a 60,000 bu. bin. That didn't not include any site prep or electrical but did include the cement. I think it took 25% down to get a CCC loan at cheap interest for 7 years. 

We do not do any HTA's with anybody. We hedge everything on the board and when we can get a good basis and we have taken a bunch of carry from the market we will do a cash contract with someone and lift the hedges. Most end users do not give a good basis bid until it gets closer to the time that they need the grain. For example we have one place paying -.40 right now for Jan, and Feb but they are at -.45 for April and May. I would bet that days after they switch to the May contracts their basis will come in line for April and May but at this time they are more concerned about the near by time frame. We also typically end up hauling about 30 miles or more in order to get a better bid from a different market. We do not have time to haul that far in the fall so we would end up taking what our local elevator pays at that time. 

I also bought some ethanol shares that would have paid way better then the bins but they both have good ROI's and you never know for sure what is going to happen in the future. If the government would have changed the RFS the ethanol shares could have turned out way different and then the bins would have looked like the better investment.