The difference in anti depressants

I have taken Luvox in the past with very good success. Last October I went back on an antidepressant, which my dr perscriped. She said at the time Luvox was no longer available. I am not seeing that this is true on forums. I had just lost my mother in law and was laid off from my advertising job w/ no insurance.  I guess maybe she thought since I just have sever anxity and depression that this wasnt the drug for me and that it would be the cheaper way to go. So I have been on Celexa. I started out with the 20 mg does and am now up to 40. I cant help but feel like its just not doing what I need it to do. Somedays I am extremely unmotivated and moody. I also notice the later I take it the harder it is to get up, but my biggest issue with it is that I grit my teeth at night now and frequently wake up with my jaw hurting. My question is what is the difference between Celexa and Luvox and would it be a problem for me to switch to the Luvox(or Luvox CR) and what is the difference in cost? The celexa is $4.00 at Walmart.