Never fuck around with braking systems. Absolute most critical part of a car. Never, ever, ever allow brakes to be unsafe. Period. If the reservoir was empty when you added fluid, that means there's air in the lines now. Air compresses, brake fluid doesn't. Brakes don't work well (or at all in some cases) with air in the lines. You probably just need to bleed them now.
Bonnie is right. You can get a lot of car for $4000. Take it from somebody who's been $30k in debt because of cars a lot recently: Don't owe money if you don't need to. It sucks. Really, really sucks. Running over people sucks too. Personal experience speaking there. In fact, running over people sucks worse than owing people money. In fact, it can lead to (court mandated) owing money. ugh.
I spent all fucking day today trying to get out of aforementioned vehicle-related debt. That sucks too. It seems like a pretty simple idea, but nooooooooo doesn't work out that way. The dealers that have the (much cheaper) car I want - won't give me jack shit for mine.
"$18,500? What the fuck are you smoking buddy? You've got an older, beat up one that you're asking 26 for. What do you think I'm fucking blind?"
"18,5 is book."
"You can sell it for 26, what the fuck is wrong with you?"
"Well, ...blah blah blah... not making any money ...blah blah blah..." (this is when I decide I should leave, before I rip the little fucker limb for limb and beat the manager with his bloody torso.)
"Well, we can get you that '99 and your payments will be $290"
"I don't want a '99. I want an early nineties."
"We can give you a better vehicle ...blah blah blah...."
"I'm trying to get out of debt, dillweed. Didn't you hear me? I don't want to pay $290 for the next decade."
"This is the owner, maybe he can work this out."
"You don't have what I want"
"Blah blah blah"
My favorite of the day:
"This thing's beat to shit. I'm not giving you five grand for it."
"Well, fourteen year old ...blah blah... not making any money ...blah blah..."
"Well, what would make you happy?"
"Hah hah, find one for three."
"Won't be hard as thrashed as that one is."
"Well good luck!"
"How about $4,500?"
"How about three?"
"I can go $4,150."
"Good for you. Maybe it'll be three grand after it sits on your lot another month. Bye."
I fucking hate car dealers.