The only way I can see you having problems in the "buying process" is if you want a car that they don't have in stock. Typically a weekday at the end of the month is an excellent time to buy a car - but it has to be a car that the dealer has in stock.
If you've been to the dealer, know the car you want is/will be there, have the money to put down, and get the job, you should have any problem getting a great deal.
I might be wrong, as I'm not that familiar with Lexus dealers..
Hey wxup 5 well im kind of in the same boat as you when I wanted to buy a car. With my experience they were very intrigued when they saw that I had a big down payment and that I worked two jobs for about 4 years. An offer that you cant turn away from would be five percent over invoice. I don't know if you would actually be able to achieve this if the dealer knows you really want the car. If he/she knows that you want the car really bad its hard to bargain. Play it cool.