[ainarssems]

Ebay is the obvious place, not sure what you mean with i4, assume it's typo for i3. It's hard to tell what you mean by semi decent. There now a lot of generations of i processors so a newer i3 might be better than old i5

I have always been a fan of IBM / Lenovo Thinkpad business class laptops not to be confused with cheap rubbish consumer Lenovo. Thinkpads are also somewhat spill proof with drain channels if you spill something on keybord it just goes through laptop and doe not touch internal components, the chances are keybooard might still fail but at least internals are protected. T440, T450 are older and should come under budget, T460 probably a bit more and T470, 480 will be more expensive. I like the 14" screen on them as well, makes the laptop smaller without going too small. You could also consider older generations of Carbon X1. Make sure you go for FHD screen and consider if you want/ need it to be touchscreen as well. As with all 2nd hand laptops battery condition is needs to be taken into consideration and I also find business class batteries to last much longer so need to think about if you want battery to last or will it be plugged in all the time or if you are prepared to replace it. I have about 7 years old T 440 and internal battery is still fine, had to replace external one after kids soaked it and was left like it overninght, the keyboard and the rest was fine, they have spilled something on it several times and no problems. Replaced keyboard eventually due to missing keys. Also my old business class Lifebook E8020D is about 15 years old and it can still run on batterry for about 1hour but on most cheap laptops batteries fail after 2-3 years.

Edit
Just make it clear I am not offering any of mine for sale, just sharing the expierence