ok lets start...

1. when i register with a real email and password and click Continue button page is blank.
2. i go to product http://www.cheaperinbitcoins.com/product?id=2817 and see in right column: Cost Overview
Radeon HD6750 1GB GDDR5 VT
Sub-Total: Ƀ 39.05
Shipping Cost Ƀ 2.74
Total: Ƀ 41.79
"View Cart" "Checkout"
when click on button View Cart my cart is empty
when click on Checkout the system redirect me to put my shipping address and actual to do a checkout on EMPTY cart  
     21. my zip code ( 7001 ) is valide for my country ( i am not in US ). your system not accept it !!!
     2b. your wizzard need to keep my choose. When i select a shipping or mayment method
     2c. of course it not allow me to checkout when my cart is empty but on a first place it not suppose to send me on this form.
3. when I add product in a shopping card i see message:
Added product to cart!
Continue browsing in the "Cases/Enclosures" section
Back to product page
When click on "Continue browsing in the "Cases/Enclosures" section" i see: "404 Error: Page was not found" - you need to fix it
4. I add a review for http://www.cheaperinbitcoins.com/product.php?id=2799 but it not show and the form to add dissapear.
    4a. Need to reload the page to show the review with -2.5 out of 5 Stars! when i add a review on a first place i add -50 scores.
    4b. it seems that to write a review i need first to add it in the shopping cart. Why? maybe after i actual buy it but just to add in the shopping cart...
    4c. Note: HTML is not translated! WRONG see product http://www.cheaperinbitcoins.com/product.php?id=2522 where i add a link to my site in a review  
5. I have 3 items in my shopping cart now. when move my mouse to your shopping cart button i see 0 items
6. click search button, click advance search and the page where i am is just reloaded.
7. Account Details. Zipcode (Also detects your state/country) - i suppose only for US
8. i select a product and qty 999 to add in my cart i see they all is listed in the cart. can you group it ?
9. i am here: http://www.cheaperinbitcoins.com/product.php?id=2799 when click on HOME ( Home > Nvidia HAF-X edition  ) same page is reload
10. i try to checkout with this products and see this error: Shopping cart failed to checkout, Please contact us at support@cheaperinbitcoins if this problem continues to persist. Otherwise try again later.
    10a. my cart was automatic cleared. but i see in invoices that i need to pay Total Cost    ฿105,977.06   i not will  

1 BTC for you my friend!

*Search/advanced search has already been found
*Tapping search options isn't breaking the website (thanks for suggesting the annoyance this will be fixed after all the bugs have been found)
*I thought math was universal in every country? could you maybe link or have someone confirm that the "," is used as a decimal in some countries?
*Zipcodes can be valid up to 10 places and some zip codes even have "+"

Try to create a new user with a valid email and a password like: ' OR 1=1; will result in a 500 server error. You do use prepared statements for your sql stuff, don't you? Donations happily accepted at 1KbwFRcCBvjbeTpho539bgN9GeSN9AFixp.

edit: doesn't work now anymore.

in regards to netrin's post... My thoughts are closely related to yours as well.
We need a FDIC insurer but for Bitcoin is really what we need.