Yeah, I collected them as a kid. I loved them. They were a nickle a pack back in 1973. One day at the local carry-out, the phone booth outside the store wasn't working properly, so whenever someone made a call, their change (and then some) would be returned, even if the call connected. Of course, the caller didn't know this, so us kids just waited for them to leave and we took turns getting the 10 or 15 cents in the coin return and then going into the store and buying Wacky Packages with it.
We also got them by "bottling": Going around to the construction sites and collecting glass soda bottles for 5 cents return. (Our neighborhood was new then and all the new homesites would be strewn with bottles at the end of the day)
I remember having almost the complete set from that year except Livirus - which was a mouthwash that had dead fish skeletons in it. That was the hardest cards to get.
Others I remember from that year are Liptorn (Lipton), Burpsi Cola, 6-Up ("It hates you and you hate it").