i'm also searching a barcode reader app for my phone ,but i 'm also wondering does it can scan all types of barcodes such as qr code,pdf-417 ,code 39 ,code 128,upc,ean-13 etc?
First of all, nice necro 
Second, there are a lot of apps out there that scan barcodes.
Some of them also already compare prices.
So, what exactly is it you're looking for?
From your (hidden) link it seems you're actually looking for an API or library, so you might want to have a look at
http://code.google.com/p/zxing/