@Chebelsebee It's not that Sims 3 can't run on low-end hardware, not exactly. There are a few different elements that play a part. One is that some expansion packs are much more demanding than others, so a computer that could run the base game and Ambitions or Late Night perfectly fine might constantly crash if it also had to run Pets or Seasons. Supernatural is somewhere in the middle: not nearly as demanding as Pets, significantly more so than the oldest packs. If you're fine with possibly or probably not being able to play with Pets, Seasons, Isla Paradiso, or Into the Future, the minimum hardware you'd need drops down a level.
Another factor is that Sims 3 doesn't run well on newer low-end hardware, for various reasons. One obvious one is that it can only use two cores of a processor. So if you have a new 4-core CPU with a lower clock rate, it's likely significantly more powerful than an older dual-core CPU with a higher clock rate, since other tasks will use all four cores at once. Sims 3 won't though, so the question is only about how fast two cores can run for extended periods. Additionally, some laptop processors, for example the Celeron line, have a higher "burst frequency" that they can hit when necessary, but they're not built to sustain that speed. So they do fine on tasks that are intermittently demanding, but not so much with games that require a higher constant speed.
The other issue is that laptops are built differently enough that the same configurations don't always handle the game exactly the same. For a given processor and integrated chip, some people play with most packs together on medium settings, only making a few compromises like disabling snow and avoiding long-haired pets; some have to uninstall half their packs to get decent gameplay; some get frequent crashes no matter what they do. Given the variation not just from one model laptop to another but also often from one year to another, it's really difficult to predict in advance how a given machine that's in this range will perform.
As an example of one such laptop, this one is on sale (only through today) for $550. It doesn't have a lot of drive space, but it should be more than enough for both games if you're not into massive piles of custom content. Its processor and integrated graphics chip are the kind where, on average, the most demanding expansions don't do well but a few of the moderate ones (Supernatural included) are typically fine.
https://www.bestbuy.ca/en-ca/product/hp-15-6-touchscreen-laptop-natural-silver-amd-ryzen-5-3450u-256...
This is the kind of entry-level gaming laptop that should run Sims 3 (and Sims 4) on ultra settings. This one is sold out now, but it's an example of the price ($750, again on sale today) you might see if you're willing to buy open-box and keep checking the sites for sales or new inventory.
https://www.bestbuy.ca/en-ca/product/asus-tuf-15-6-gaming-laptop-black-amd-ryzen-5-3550h-512gb-ssd-8...
If and when you're ready to buy and have a preferred price range in mind, I'd be happy to do a more thorough search. There's not much point in doing one now though because things change so quickly. A laptop that you like right now might be $100 more expensive in a month, or $100 cheaper, or it might not be available at all.
By the way, the easy part of this is you don't have to worry about Sims 4, at least not much. If you get a laptop that can run Sims 3 with any success, it should also run Sims 4, albeit perhaps on lower settings. Sims 4 scales down much better than Sims 3 and is also built to take better advantage of modern-ish hardware.
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I don't work for EA. I'm just trying to help fellow players with their games.
nothing ridged (if it's not affordable right now, just means wait time). 
