Boy sometimes it's hard to help... Don't always believe the crap that the dealer tells you.

How do you know your car is out of alignment ?
A) Is the steering wheel turned left or right from horizontal when you are driving in a straight line ?
B) does your car drift left or right when you take you hands off the steering wheel on a flat and level road ?
C) does your ride feel bumpy when you're driving on a flat, level road ?
D) does the car pull left or right when you apply the brake ?

Not all of these things mean you need and alignment. First thing, drive down a flat level road in a straight line. look to see if the horizontal part of your steering wheel is level with the horizon when you are traveling straight. Answer all the above questions and I can probably fess out this problem for you. If it was a rental prior to your purchase,, I would bet that your wheels are out of round (bent) or the wheel balance is off, not necessarily the alignment.

Lastly, the alignment and camber bolts take about 1-1/2 hours, oil change is 10 minutes and about $90 at one of those quick lube places (and yes, if you have them stamp your maintenance manual when you get the oil change, it won't void your warranty)... Why do you need a rental car for a few days ?