<form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="HFDCDGQSWQJ52">
<table>
<tr><td><input type="hidden" name="on0" value="Sizes">Sizes</td></tr><tr><td><select name="os0">
    <option value="8x10">8x10 $350.00 USD</option>
    <option value="12x15">12x15 $500.00 USD</option>
</select> </td></tr>
</table>
<input type="hidden" name="currency_code" value="USD">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_cart_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>