best way to obtain old games sort of cheep?

[yt fungal gaming]

so like most of you i collect/restore older games,mostly focus on the ps2 because thats my favorite console of all time but now here is the real question. what is the best way to obtain a lot of games sort of cheep? i go to thrift stores quite oftan as the one by me has them for $2 on Friday but i really just find sports games and the rare good one. i have a goal in life to try to own every ps2 game made or as close to it as i can get but places like eaby people ask up to $10 plus for most games. any tips from the more experienced collectors?

[Megatron]

If you're going for bulk, try looking for "lots" or bundles.  You may pay a larger price, but $100 might get you a pretty good pile of titles.  
I collect Genesis titles, and a few years ago I found a sale of about 100 games for $300.  A lot of money, until you realize that it included TMNT Hyperstone, Phantasy Star 4, and a handful of other pricey titles that more than makes up for the cost.

Also, if you're looking online, craigslist, mercari, and offerup are usually better than eBay for prices.  eBay has the selection, but prices are market value or higher.  These other sites/aps are more likely to find a seller not asking top dollar.  

[Bear78]

Flea Markets / Toy Shows!  My absolute best finds have all came from Flea Markets / Toy shows in my time collecting.  Really it's all been about putting in the effort to go look for stuff for me.  Beyond that, mom and pop shops and independent game stores have also been good sources.

As Megatron said, buying in lots can help a lot.  I'd throw out Facebook marketplace as a spot to check too.  I haven't personally used it but I know a lot of collectors that have had good luck with it.  Also look for local collector groups (on Facebook) that you can get involved with.  I'm in the St. Louis area and there's a great collectors group on Facebook that helps each other out.