I mean this in all seriousness. Do not skimp on a firearm. Do not buy a hi-point, Jennings, Lorcin, etc.
The minimum that I have seen decent handguns go for is around $300 used, $450-550 new. Expect to spend that much. If you can't afford it, save up and buy quality, do not buy crap because it is all you can afford now.
Here are some quality brands that are not too expensive.
Glock
Springfield
Taurus
Colt
Beretta
Ruger
S&W
Kahr
There are plenty of others I just can't think right now, I just spent the last 4 hours tuning my XDM match trigger.
Expect to spend between $300 and $600 for a quality weapon that will function fine and won't break the bank. You will just have to go to a shop, feel around and see what you like, what fits your hand well, rent some and shoot them if you can, much of it is personal preference. For instance I think Glocks are fine guns but I hate them because they feel so awful in my hand and I can't hit jack with them. However here are some suggestions. Try a Glock 19 and see how you like it, also try a Springfield XD 9mm which will feel much different due to the grip angle and dimensions, try a S&W MP they are nice too and a Kahr. If you don't like those then you don't like striker pistols, move on to hammer pistols like a Beretta 92F or a Taurus or Ruger p89. My sidearms are upper eschelon like SIG, HK, Springfield XDM, but they are also more expensive. Asking what the best pistol is is like asking what the best car is or what the best shoe is, there is no right answer, different guns are geared toward different characteristics and they have different personalities, you just have to see which ones you get along with. As far as caliber you basically have 3 choices for serious consideration 9mm, .40 S&W, and .45 ACP. For a first gun I would go with a 9mm, it's cheaper, easier to learn to shoot on, the most popular and widely available pistol caliber, highest capacity, highest shooting perfomance and with high performance ammunition almost as terminally effective as .40 and .45, the differences seem to shrink a little more every year. I myself have gone from .45 for the longest time, to .40, to 9mm. My XDM is both .40 and 9mm depending on barrel and magazine and it has the remarkable ability to make the .40 recoil like a 9mm, so it come down to ammo cost and capacity. I have also gone from hammer pistols to strikers for the uniform and consistent trigger pull.
I must also mention if you decide on a revolver, go with .357 mag.