I haven't read the whole thread. So, excuse me if this was covered.
I wouldn't buy the used 75b. I would find an FFL that does low priced transfers. Then I would order a brand new CZ P-07 Duty from Jet Guns. You would be out the door for about $440 total. $15 isn't too much more and you get the comfort of a new gun with full waranty.
It is a polymer compact with a slide milled from a single piece of bar stock. It has the Omega trigger which marginally improves the DA trigger pull. Plus, you can swap the decocker for a manual safety. Not to mention it weighs half a pound less than the 75B.
Then when the money situation improves go hog wild on buying the big boy. For now though the smaller P-07 may prove to be more versatile. I have carried mine aas my cch three or four times. With a better holster and belt it wouldn't be too taxing. I couldn't imagine toting a 75b as my ccw.