If you're interested in buying secondhand laptops, I strongly recommend you look at any "business-class" model from any manufacturer. Laptops that cost $1,000+ and are aimed at business fleets, rather than individual consumers. These laptops tend to be very well-made, are designed for commonly-broken parts to be easily replaceable, and are widely available secondhand as companies update their laptop fleets. Here's an incomplete list of manufacturers and series:

* Dell Latitude (except the budget 3xxx models) and Precision * HP EliteBook and ProBook * Lenovo ThinkPad X, T, and P series (in order from small & light to big & powerful) * Panasonic ToughBook (rugged!) and Let’s Note * Fujitsu Lifebook * Acer TravelMate and Extensa * Asus ExpertBook * Toshibe Portege and Tecra * Epson Endeavor