Estimates are that 80% of your energy is to overcome aero drag. So, aerobars are highly encouraged.
However, I'd not get that bike. Get a used tri bike (
a motobecane tri frame just sold on ebay for $125 buy it now). You could have a very decent bike for under $300.
You just have to keep your eye out. Also, CL has some great deals. Get an old road bike and then get some
aerobars like these or
these
Dont pay $100 for a pair of aerobars until you know you like the sport and get more serious.
Something like this might be a good cheap base bike:
http://raleigh.craigslist.org/bik/1515606849.html