I made this up for the newbies based on Site Pass AVS - but you can use it for any AVS system with a premium and regular level. Just adjust the number of pics for the premium site and then work your way down adjusting the lower levels accordingly.
Linking them all together? Just link up - use the galleries to upsell to the "free" pass level site, use the "free" pass level site to upsell to the "regular" pass level site, use the "regular" pass level site to upsell to the "premium" level site.
Once you get ONE of these structures made, start a hub listing off all of the different sites. Every time you make a new structure, add the sites to the hub.