Reading your tags it seems like you are looking into something with iOS and Android support.
I use Myibidder for my own sniping purposes. It's available for iOS (offers both iPad and iPhone support) and Android as well.
I like it because it allows me to browse eBay and import my Watch List, and also supports groups (where you set a number of snipes, then ...
When I last used Windows on an old Laptop, I used TurboLister for this. Was really convenient (miss something like that on Linux now):
TurboLister (click images for larger variants)
Let's see how it meets your requirements:
Windows 7/8 compatible: its homepage states at least Windows 7 compatibility.
upload images: yes.
save products locally ...
I did research about webshops and found that Magento seems the best choice. Did you look at Magento ? It's PHP with rdbms backend. There are also other similar project, but AFAIK magento is the best, since it is the most mature and has the most complete set of functions and interoperability with other vendors, if you want to host your own webshop and can run ...