A CCW license for your locality IS the SHTF answer. 48 states and growing doesn't make it a right that might go away, it makes it a realization that good people are having to deal with this stuff now.
Gun? Glock 9MM's. Revolvers aren't high capacity enough. In a recent gun mag article, Glocks rated consistently in the top ten guns tested for hit probability. .45's did better, Glocks are much more affordable. 9MM is about the cheapest round out there - you can afford to practice, which is a requirement. Just carrying is useless if you don't know when it's necessary, and how to actually hit a target. And most double action revolvers don't hit that accurately, as the same article showed. It takes too much practice to learn how to keep from wiggling around. A laser to learn quicker is out of the budget.
Police trade-ins are an excellent value for the money. There are SIGs on the market now for $360. Check the gun trade advert magazines, or online guns for sale auction sites.
A good primer on the magazine rack right now is G&A's "Personal Defense" magazine. Everyone needs to refresh on Mas Ayoob's article on legal Do's and Don'ts. Sometimes, the REAL SHTF when the lawsuit is dropped on you, even though you thought you did it all correctly.