Can't buy apps from PC?

I have no wireless coverage at work so I can't purchase apps from my PB when I'm in the field. I do have wired internet to my notebook and I've been browsing the online app store.

The apps show the option to purchase, which I assume means they'd be downloaded to my computer and then loaded onto the PB over the desktop manager; but whenever I log in with my BB ID to try to purchase a PB app the store only sees that I have a Bold 9900 and tells me that app isn't available for my device (duh).

How do I get around this?

It will be good to know if it is possible...