My last laptop was a used 2012 T530.

My current is a used M1 MBP Pro with 16GB of ram.

I thought this was all I was ever going to need, but wanting to run really nice models locally has me thinking about upgrading.

Although, part of me wants to see how far I could get with my trusty laptop.

Your current laptop is still a fine thin client. Unless you program in the woods, it's probably cheapest to build a home inference box and route it over Tailscale or something.