I recently purchased a Diamondback Lux Sport at Dicks Sporting Goods, after waiting a week for it to arrive it turns out they shipped the wrong bike. Now that the mistake has been noticed, the bike is sold out... It was on sale from $799 down to $400! I need a small frame bike...I'm 5'5"

I'm going from a random store bought hundred dollar mountain bike to something we can use in the old mines that have been converted to mountain bike parks here in Florida...we mostly bike Alafia, and are shocked my cheap bike has lived through 2 years of that park!
I mostly just ride blue tracks... A couple of black diamonds here and there, but I like my teeth, and bones!

I want something decent obviously, but I don't want to spend a ton of money. I'm now forced to look for another option... I've seen the Dawes the Motobecane and the GT brand bikes have some bikes in that same price range.
I realize just about anything is better than what I own, however I got so excited about getting the nicer bike....that now I'm completely confused on where to go.

FYI our local bike shops generally carry hybrid bikes... I do not want to hybrid!

Thanks in advance