First of all, this is the
WRONG PLACE to ask for financial advice. Your talking about a forum full of mostly...errr... hmm... less-than-middle-class rural Americans (didn't offend anyone, I hope?) spending waaaay too much on a knife hobby. Not to insult anybody, but it's the damned truth, and needs to be said since you are a young man asking for financial advice. This is the WRONG PLACE to ask for it. There are places on the internet where financially-savvy people congregate and help each other. This is
not one of them. Now then, if you've got a knife that needs identifying, or if you need to know how a certain year's model of a certain Buck knife performs while batonning through a certain material type... this is THE only place to ask.
But... if you insist on advice, then I'll shoot (although you should take my advice with a big grain or two of salt, too!): I think you are wise to consider that Taurus. First, ask the owner why he's selling it and why is the price so low? Is there a major issue with it? Test drive it. The best way to get a sense of the condition of the car if you are not a mechanic is to listen to it. Start it up, let it idle for a while, drive it around the block, try the brakes out. How does the car sound? If it sounds good and smooth, it usually is. If it is making weird noises (grinding, squealing, knocking, etc.), something is wrong. Before you buy it, google repair shops near your zipcode and choose one with a good reputation and good reviews. Take the car there and get an honest opinion on any mechanical and electronic problems (burning oil? transmission bad? engine light always on? brakes still good? tires still got tread?), before you buy. If your $1500 car will need new brakes and tires within a few months, then it's actually a $2500 car. If you decide to buy, resolve to take care of it: let it warm up in the morning for 5 minutes before you drive, go easy on the brakes, change the oil every 3k miles, get a tire-pressure gauge and check the tire-pressure once in a while and make sure it's correct, check the oil every two or three days for the first week or so so make sure it's not burning up oil and/or the oil isn't getting mucked up fast.
But by spending a few more G's, you'll get a much better car. You mentioned that your grandma was willing to help you out. Is she willing to give you a loan instead of cosigning a loan? If you can borrow 2K from your grandma and spend $3,500, you'll get 10x the car. Plus, you can pay grandma back as you are able without hurting your credit score.
Finally:
don't get a loan and always live below your means. Example: just because you've got a little extra cash this week and you can afford Velveeta & Shells and Heineken, doesn't mean you should buy it. Stick with Mac & Cheese and Miller and save that extra bit of cash for another day when you actually need it for something. It helps to have a goal to save money. Start small: save $50 a month. That's it. After six months, you'll have $300 in the savings account.

Any questions, just ask!