WP Photo Seller I believe will allow you to buy more than one at a time but there is no option to buy entire gallery. One feature that many lack and it is unfortunate. A photographer might shoot a small event and if clients want to buy the “entire gallery” for $x amount of money they can buy it entirely or none at all. You would have a protected gallery, client logs in, sees the watermarked photos (hard watermark not overlay which can be easily removed) and after he purchases the “entire” gallery they get a link to the digital file (zip or raw), even better after 7-14 days the zip, or gallery gets deleted.
You would also want a way to download zipped or compressed files and esp. shooting 24+ mp. you’re looking at about 8-14+mb/file JPG or 30+mb/RAW files. Many are still awaiting this feature to password protect gallery, watermark images, if clients like it, they buy entire gallery (paypal) get a return link to either local host or amazon s3.
