First off, it is doubtful people will show up at your house because you install a repeater. Under Part 95 repeaters don't have to be coordinated by an assigned FCC coordinator and listed. Your repeater operates under your call sign on GMRS. The only way you might get people showing up is if you have HOA restrictions and you violate them. Secondly, your repeater will only be available to people operating on GMRS frequencies, not FRS or Bubble Pack radios that do not require licensing. Bubble Pack Family Radio service radios are what you would find in most people's "go pack" as they are what's found at your local Wal-Mart or Best Buy.
Before spending that cash I would also do a little research and see how many potential users that could currently use your repeater. Do a search on the FCC website to see how many people are currently licensed for GMRS in your county. Expect that number to slowly grow once you install the system. People will still need to purchase GMRS radios and hopefully get licensed for them as well. Again, you aren't going to find GMRS radios in the local big box stores. Thirdly, and most importantly, you need to think about your coverage area. Talk out isn't as important as talk in or receiving signals form low power hand held radios. For that, you will need height on your antenna which means a tower or pole mounted antenna. Finally, your repeater is a LOCAL resource, it won't be of much use in an evacuation as there would be no one local to use it. It may be of use to those evacuating through your coverage area but it won't help you or your family if you leave the area.
In all actuality, I personally believe you would be better served by having you and your family get amateur Technician licenses and use the money to install both a 2 meter base and mobile system for your house and vehicle. Tech licenses are not difficult to get and the infrastructure for 2 meter VHF and 70 cm UHF repeaters is quite robust across the country. For amateur help go to the ARRL website and look up what amateur clubs are in your area. Many clubs have websites where you can look up the number of repeaters in your area. You can also use sites like Repeater Book to do an area search for repeaters. Amateur clubs will hold classes free of charge to teachthe required rules needed to be licensed and there are several free websites that offer practice tests to help you pass an exam. All this advice is worth exactly what you paid for it as it's just my opinion.
Bill WRCM737, K4BJW