My recommendations:
1. A .22 pistol or rifle; in a pistol I'd recommend the Browning Buckmarks if you don't like the Rugers. They're much better thant the Walther P22 or SIG. If you decide on the SIG I recommend you shoot CCI Mini Mags through it as the gun is VERY reliable with this particular ammo but very un reliable with other regular .22 ammo. A Ruger single six with the .22lr and .22mag cylinders is a wonderful gun but it's a gate loader so you load one round at a time, then cock the hammer and shoot each round and then unload each spent casing throught the gate so it's a very slow deliberate process. I like it but some like a semi.
2. A 9mm handgun that fits you and is reliable. For your budget there are lots and lots of choices. 9mm is fun because it's some of the cheapest centerfire ammo out there, so you can shoot more, and the recoil is very modest and yet it's a good defensive round.
3. A .22 that is a rifle if you already bought the pistol or a pistol if you got the rifle
4. A Marlin 1894C lever action rifle chambered in .357. Same ammo as the Ruger. Recoil of even hot .357's shot out of the gun is modest to downright soft with .38 Specials. It's a very good home defense gun. It's a LOT of fun to shoot. You can mount a scope on the Marlins (they have solid top receivers). You can hunt deer with it at close range and small game with the .38's but mainly it's just a beautiful and very fun gun that's not too expensive to shoot.
5. A 1911 in .45 ACP. I'd recommend a Springfield Loaded Model. Don't get a plan jane or stripped down model with the idea of "customizing it later" if you like it. You will, get it up front the way you want it. 1911's have a special power. the .45 ACP does have a good deal of kick but it's more of a push and a thump than a snap or crack which makes it more manageable to shoot.
Finally, I'd focus on select calibers and not end up with a lot of different calibers. It's costly and hard to stock up.
I love .40 for SD BUT I don't like the very snappy "crack" type recoil of a .40 so I don't have them.
I focused on 9mm .38/357 and .45 in pistols.
One last option. If you're looking for something VERY fun, cool looking, good for home self defense (although I think a handgun is best for SD), then I would recommend you consider a Berretta Storm CX4 in 9mm. Virtually no recoil, not too expensive to shoot. it's short and wonderful to handle. has great ergonomics and looks cool as all get out!!! It used very common available mags so you can get 15 or even 20 and 30 round mags for it and have a blast!!!
A lot of folks will recommend a shotgun. I do not. I do think every home should have one good shottie, but shotguns kick and kick hard unless you get an auto. Even then they kick and they tend to be heavy and the ammo is costly and bulky (well not bird shot) Ranges that allow you to shoot them are fewer and other than shooting trap or skeet you won't have the shooting opportunities you would with the other recommendations. I haven't met too many ladies who looked forward to going and shooting the shotguns!!
whew....so many guns and so little money and time
Enjoy and God Bless
Gideon