Depends what size/brand/etc you want. You can get a KelTec P-11 for $200, but that will have a lot of recoil for your wife as it's a very small gun (12+1 and almost pocket sized gun). You can get a used Ruger P89 or P95 (durable and totally fine to buy used) for $250 or new for $300-350ish. You can get a CZ 75 used for $300 or sometimes under. Taurus also makes some low priced 9mm semiautos (for example the PT-111 millenium pro that someone mentioned was about $250 locally, and they make a copy of the Beretta 92 called the PT 92, which is a full sized 9mm).
Yes, Glocks will run you $500ish, at least, for a new one. SigSauer, Heckler & Koch, Beretta, etc. are also all excellent guns, but are also very expensive.
IMO, CZs and Rugers are very economical and yet extremely durable guns for what you pay. They're a good gun for anyone. I personally prefer the CZ in that I find it more accurate and think the ergonomics (grip, etc.) feel much better in my hand, but Rugers are rugged as heck and will never fail you, either.
I did a lot of research before I bought my CZ, and I had it narrowed down to CZ (the CZ 75B) and Ruger (the P95). Then I went to the range and rented one of each the same day to compare them. I immediately decided on the CZ 75 BD and bought one used to save money (around $350-400 new) and to get one that was already broken in but still in great shape.
To get a rough idea of prices, try going to
www.budsgunshop.com and take a look around at the pistols. Also, go to your local gun shop and handle some of them. I have a few gun shops around me, and one of them is ridiculously overpriced, which is why I get an idea of prices online before I go into the stores. There are some gun auction sites (
www.gunbroker.com,
www.gunsamerica.com,
www.auctionarms.com, etc.) to get a rough idea of used prices, too. You can go to your local bookstore to look up used gun blue book values, too.
Everyone will tell you to go rent a ton of guns and try them (and that's a great idea), but the problem with that is that if you're on a budget, you'll end up spending your whole budget on gun rentals and range time. If you know someone who shoots, that's a great alternative b/c you can probably shoot their guns for free if you buy them a box of ammo. But there's a certain amount of faith involved in buying your first gun. Some people find out they love what they bought, and others realize what they DON'T like about their gun and end up buying something completely different later. It's all part of the process.
I'm totally thrilled with my CZ 75 BD. I couldn't be happier. I definitely got my money's worth, and everyone who's shot it is jealous of its accuracy and wants one.
But determine what your budget is, and we can make more specific suggestions as to what to handle in the store. Then you can narrow it down to a few and either rent them or ask on here or both, and we'll help you out.
Hope that helps!