I'm doing a similar thing for my band. I'm sure there are plenty of people on here who can tell you what brands are good and what aren't, but for starters....
With your budget, I'd definitely go second hand. Although you can usually get nearly new PA for around half the new price, I think you'll probably end up with something older for that money. If you get decent brands, reliability shouldn't be too much of a problem. Put as much as you can into the speakers and go for a vocal PA only - i.e. forget about bass cabs. A 12 and a horn is probably the optimum configuration for vocal cabs. For pubs you should be able to get away with 250 watts of amplifier power, although more is always better.
Check that all the inputs on your mixer are working and check for noise from the control knobs, especially sliders. Avoid piezos and bullet tweeters in your speakers (like in the old HH PA cabs). Make sure the horns are working on your PA cabs - listen to some music through them. There were some very cheap Peavey speakers for sale on here not so long ago that might be worth checking out.