Driving gloves. Some halfway decent calfskin gloves make it nicer to drive, whether the steering wheel is hot in the summer, cold in the winter, or if you're going to be driving long distance. Not sure if real leather will be less than $20, but seen some cheap fingerless work gloves make driving more comfortable.

Clip on sunglasses that fit on my eyeglasses. Super easy to clip on, cost about ten bucks. So nice to not have to squint as much.

Dim light bulbs. Nearly every bulb in my house is as dim as I can manage. Some are salt lamps and some are those flicker fire bulbs. Either way, it makes the light at night a little warmer and a little dimmer, and all around a lot more cozy, which really is what one wants. Keep a couple of the overhead bulbs at the brighter end in case you need them, but dimmer bulbs make me a lot happier at night.