CODE P0607- how long can I drive car until battery completely dies

Hello,
This is my first time posting here so I apologize in advance if this subject has been beat to the ground or if I'm not posting in the proper forum.
I bought a 2007 Prius Touring with a little over 149,00 miles last month and it now just has a 150,006 miles. My previous Pirus was totaled when a careless driver rear ended me. I needed a car and found one I thought fit my budget and needs. I bought it from a person who buys Priuses at auctions and sells a couple at a time (Automix Plus in St.Pete,Fl). I test drove it briefly during the day then came back a few nights later to purchase it. Within a mile of driving, the driver headlight was flickering and the next morning the tire pressure light turned on. I filled the tires, then took it for an oil change. Light went away but came back a few days later . so I took it to Tire pLus(BIG MISTAKE) where they told me it was a wheel bearing problem and quoted me $420 which i declined because i wanted to take it to the dealership to be sure. This morning three warning lights appeared: master warning light, brake system warning light, and malfunction indicator lamp. I took it to Toyota dealership where they informed me it was CODE P0607 and i need a new battery. In all the estimate was 5999.22 (brake pads,rotors, 150k maintenance, head lights,etc. Wheel bearing is fine.). I'm a student and I just paid 6,300k for the car(prior to taxes.etc) . No way can I afford to pay another $6000. My question is what are my options? How long will the car run until it completely dies? I graduate this December so I need it to at least untill March. The person I bought the car from denies knowing anything about any problems with the battery, tires, light,break pads, etc. He told me he had been monitoring the battery and everything was in good working condition. He quoted me $1500(labor included) for a rebuilt battery with a 3 year warranty. He said he could have it installed in an hour at my apartment parking lot. I 'd rather not give him anymore of my money since i feel like he must have known about these issues and chose not to be honest when I asked about the condition of the battery and car before purchasing the car. Do I have any options at this time? Thank you.

 

I just drove it home 30 miles and it ran great. It was getting 45mpg and the battery was charging. .All four warning lights are now gone after Toyota ran their 28 inspection.I was told that the warning lights would keep appearing until I replace the battery. I was shocked by the 6k repair quote so I'm still a little fuzzy on what the service manager told me . But if i recall correctly, he said that a block was malfunction. Is this a part that I can have replaced at another shop?
thanks.

 

Hybrid supply battery $3236 and hybrid vehicle control computer $780. Is it possible to just replace a cell at toyota or is that something I'll need to find a different shop? The 12v battery was checked. actual cold cranking amps:420
factory cold cranking amps:350

 

Personally, I think their estimate was outrageous. almost $800 for new front pads.

 

I will. Thanks.