Rosalie,
The Standard Plan has unlimited listings & 1GB of image hosting for the plan.(Additional image hosting space can be purchased above 1GB). (totally unrelated to the # of pictures per listing).
Individual listings are limited to 24 pictures max per listing, that is correct. That seems like quite a lot of photos for one auction/listing, but I understand you have 70 pcs. Maybe there's some way you can find to group them that will display them well.
You could host add't pictures on photobucket and create a link for the buyer to view the add't pics. Or ask your buyer to email you for add't pictures (include that in your listing).
I know & understand that's add't work..but it is a work around. I can understand you want your items to show well..but seems like 24 pictures should be enough. But, that's an individual thing I realize.
Good luck..