I stopped going after lots as I entered '60s cards. Effective collecting strategies seem to change with different eras. Purchasing lots while collecting '70s cards presented an opportunity to obtain value. That doesn't really seem to be the case with '60s cards in my experience. People just aren't selling decently priced lots online when you calculate price per card.
You almost get a better deal collecting '60s cards individually, than by looking for lots. You'll most likely have to change your strategy to be successful in collecting '60s sets. It probably does have something to do with the cards being broken down into series. It probably also has something to do with the wide variations of card condition that prevent people from lumping a pile of cards into a single lot (people can be sticklers on condition uniformity, I guess). The one thing I know, is that lots aren't "in the cards" for effective set building strategies for '60s cards.
1968 and 1969 Topps might still present an opportunity to collect a few lots, but after that, it's going to be card-by-card. One exception is if you start a particular set off with a large lot. There is one vintage lot seller on Ebay named CountryRaisedDad:
https://www.ebay.com/sch/countryraiseddad/m.html?ssPageName=STRK%3AMEFSXS%3AMESOI&_trksid=p2053788.m1543.l2654
He used to start everything at $0.99, so I would get good deals if no one else was looking. He used to list his lots in PR condition, but what I got looked more like VG-EX. He helped me start a lot of my '50s-'60s set, but after that, it's back to card-by-card.
Unless you have access to a large card show, Sportslot seems to be the best way to get decently-priced commons for 1969 Topps.