Now this I like! I totally like the layout of the landing page, especially the background image. Is it not possible for you to use a wider image instead of tiling it? I wonder though, how fast it would load on a slow connection.
Btw, your homepage lacks a title, which is an indicator that SEO is probably not top on your list.
The background color/image of the inside pages is really soft on the eyes, plus the contrast with the text is good.
I vaguely remember reading that the right side of the screen is usually a hot spot, so, if i were you, for the inside pages, I would use the right side to highlight "featured" products or deals, then move the login/register thingy to the top, like it is on the landing page. This will have the added advantage of maintaining visual consistency.
Then, go a step further and once the user logs in, since you will be tracking what each user buys/sells, then you can use the right side to show items in line with the user tastes, thereby succeed in making users feel as is they are being watched :-)
One thing I did notice is that the top, right and bottom paddings of the search button inside the search box is uneven.
If you go here http://mzoori.com/product/73/free-installation-for-car-tracking-systems you will see that the item is "Listed Under [Parent]"