I bought a Walmart bike once, nothing was adjusted well and every nut/bolt loose. It just fell apart.
I got my next bike at REI, great service, I got to ride it all around for as long as I wanted, well set up, adjustments perfect, I got the 27 inch wheels and they make me feel like I am really up there was about $250-275. still works good, I got a non suspension bike.
Carl