Anything in the *80 series or newer is WELL worth the extra money. *70s and below are typically dual cores unless you get high end "workstation" tier machines. Dual cores are usable, but quad core machines are really the bare minimum you want for a truly good experience dealing with the modern web.

My preference is generally to stick with the X and T series of machines. W and P series carry a premium because they're the highest end workstations (I do love my P1, but that was almost 4k USD). T4XX and T14 are the most common models you'll see used, but the T5XX and T15/T16 machines are less common, but also less in demand so they can be cheaper. There is the P15s/P16s which are literally just their T series counterparts, just with an ISV certification, and quadro video cards instead of geforce.

I'd also HIGHLY suggest avoiding "refurbished" machines. You're paying a premium for someone to wipe the computer down for you. They're not replacing any parts, you're just getting a used computer. The only refurbished machines I'd buy are straight from the manufacturer. And you're buying a ThinkPad so a warranty shouldn't be needed. As long as it works when you get it, it should only fail if you broke it.

Finally actual model advice. The T480 is the first machine with a quadcore CPU, but also the last (until lately) with 2 ram slots. It's also the oldest machine to natively support windows 11. Irrelevant to you, but relevant to the price of the machine. At least in the US most ThinkPads bottom out at about $200 (USD) and only dip below that if they're broken or too old to run windows 11. The T490 is the exact same thing, but only 1 socketed ram slot and the other half of the ram is soldered, but they're MUCH cheaper. I got a T14 Gen. 1 about 2 years ago for $200 USD, and about a year ago I got a T14 gen 3 for $250. Don't be afraid to look newer, they might be cheaper. T490 and T14 gen 1 might just be close enough to your price range.

Also if you can try looking on local classified ads. Prices online will almost always be higher because the marketplace takes a cut of the sales price. I only get good deals on Facebook Marketplace, and Craigslist. I'm not sure what's popular in your area, but try that.

I have a T480 that I bought a few years ago for around $250 (~€217). There are a number of possible configurations, but the one I bought was an i7 with 16 GB RAM, and a 256 GB SSD. I replaced the drive with a 1 TB SSD, so that was another $100 (~€87). Prices on this model have gone down since I bought mine as it is about 8 years old. I still highly recommend one since it can be upgraded to 64 GB RAM and has a removable battery, unlike many newer models. Just make sure it's a T480 and not a T480s. The T480s doesn't have upgradable RAM or a removable battery.

I have an x270 with around those same specs that I use happily every day. I've never bought new batteries though, so it would not be a candidate for the bus realistically for me. I run a few simple games on it (like Stardew Valley). I use Xfce, so fairly lightweight, but I think I could run something a bit heavier too, as it feels very snappy. Beware of bad audio though, that was such a disappointment even when it was new-ish (bought it very lightly used).

I would be willing to rebuy my laptop for around 1500 NOK now.

I have a T440S with 8GB RAM and a mechanical 500GB that I bought in an African computer shop about 7 years ago. The computer has a Swedish oriented keyboard, but I hooked it up to a big 44 inch HD screen using an adaptive connector. Works fine. I run the latest Debian, with Niri, and I had to configure Out-of-Memory Killer (which was necessary given what I do). I'm saving up for an upgrade, which I should have done a long time ago, but I haven't thought it through.

Now, based off the information presented, that T450S looks the part. If it has a mechanical drive, I would replace that at some point if needed, but I would likely pick it over the X270 which costs slightly more. The display matters, so you have to see what works for you, given preference. I think the T450S has a bigger display.

If i can find an X280 for 170€ then so can you. The RAM crisis may have made things worse (Mine was bought in October last year...), but if you wait a while for a good auction you should be able to get one for an even lower price.

Im seeing a listing for 200€ right now (in Germany) with 17 refurbished ones in stock: https://www.ebay.de/itm/137560326768 I have bought ~10 thinkpads for other people through ebay and never had any issues beyond some scratches on the housing and one scratch on the display that was mentioned in the description. You just always have to read carefully.

Like this one i added says: “The devices are in very good condition, both technically and visually. The casing may show some signs of wear (minor scratches, no structural damage).” These bulk sales often come from dissolved businesses so they are usually in very pristine condition. Sometimes a battery swap makes sense though if you use it while traveling/moving location a lot.

I really wouldn't get anything with a 6th gen core or older, you're really gonna notice the age of those CPUs in day to day use.

For 200 €, it's possible to find T14/L14 Gen1 and Gen2 ThinkPads on used sites like Kleinanzeigen in Germany. the T14 is built a bit better, but usually also more expensive. The L14 has two RAM slots, the T14 has one slot and one "module" soldered. Then there's also the T14s and L14s, which are a bit slimmer. Beware that all T14s models have fully soldered RAM, I'm not sure about the L14s.

My recommendation would be to scour used sites and get an L14 Gen 2 with an i5 11th gen, 256 GB SSD and 16 GB RAM or better. It might take a few weeks of waiting, but at least in Germany it's doable for 200 €. And an 11th gen i5 is going to run absolute laps around and i5 6th or i7 5th gen.