The bulk sponsorship purchase page is linked with the text "Buy Articles" in the front page template. This links to index.php?action=bulksponsor, which can be customized in the "bulk sponsorship" template at Admin -> Themes -> Manage Templates. The purchaser selects a article type from among the sponsored types, and then selects a quantity to buy. Upon purchase they're automatically redirected to the submit article page which will automatically process their submission as a paid sponsored article.
You can set bulk discounts with your bulk sponsorship, so that buying several articles at once costs less than buying them one at a time. When adding a article type sponsorship level at Admin -> Revenue -> Sponsorship, click the "Add Bulk Pricing Range" option to do so.
When the bulk-sponsored articles expire, at present they can only be renewed separately one at a time at the undiscounted price -- so best used with longer term sponsorships.
There are a few template variables you can use to display more information about someone's bulk sponsorships:
{MEMBERBULKPURCHASEDTOTAL} - The number of submissions they bulk purchased.
{MEMBERBULKPURCHASEDUSED} - The number of bulk purchased submissions they've done so far.
{MEMBERBULKPURCHASEDREMAINING} - The number of bulk purchased submissions they have left.
{MEMBERBULKPURCHASEDTYPE} - The article type they've bulk purchased.
These also work as {THISMEMBER for the person viewing the page, so to show them the number of submissions they have left you'd do this:
<IF {THISMEMBERBULKPURCHASEDTOTAL} and {THISMEMBERBULKPURCHASEDREMAINING}>
<p>You can make {THISMEMBERBULKPURCHASEDREMAINING} more {THISMEMBERBULKPURCHASEDTYPE} submissions: <a href="suggest.php?action=addlink">Submit</a></p>
<ELSE IF {THISMEMBERBULKPURCHASEDTOTAL}>
<p>You've used up all your bulk submissions: <a href="index.php?action=bulksponsor">Buy More</a></p>
<ELSE>
<p>You haven't purchased any submissions: <a href="index.php?action=bulksponsor">Buy Some</a></p>
</IF>
<p>You can make {THISMEMBERBULKPURCHASEDREMAINING} more {THISMEMBERBULKPURCHASEDTYPE} submissions: <a href="suggest.php?action=addlink">Submit</a></p>
<ELSE IF {THISMEMBERBULKPURCHASEDTOTAL}>
<p>You've used up all your bulk submissions: <a href="index.php?action=bulksponsor">Buy More</a></p>
<ELSE>
<p>You haven't purchased any submissions: <a href="index.php?action=bulksponsor">Buy Some</a></p>
</IF>