Might be slightly over, but some cheap loadable dumbbells. I was never a weights guy, but these made it so I could get a simple workout in at home between meetings. They are annoying to change weights on, but everything is just a solid piece of metal, so they'll last forever.

I'm by no means a strong guy, but I've significantly increased the weight I can lift over the course of the last year. For me, it's really awesome. My biceps and triceps have also gotten way more defined and it's really cool when people notice. Feels good to see a more physically defined body in the mirror.