Take the technology behind Citizen's Eco-Drive watches, cram it inside a hip and colorful case reminiscent of Swatch watches from way back, and slap it with an affordable pricetag. What you get is the Q&Q SmileSolar, a maintenance-free timepiece that never needs winding or a fresh change of batteries.
Sure, it brings none of the sophistication of full-fledged Eco-Drive timepieces with their satellite signal reception and premium construction. It does get the same solar-charging abilty, though, able to replenish its power stores from both natural and ambient lighting sources.
The Q&Q SmileSolar uses ABS resin for the case and polyurethane resin for the strap (all partly-recycled), so this is no classy timepiece for pairing with your dapper threads. They do have models that eschew the extra-bright color scheme (like an all-black one), however, so it might still work if you needed a watch and couldn't find the Omega JFK Watch that you wear to make you feel stately and dignified. Watch details include a 40 x 12.5 mm case, water resistance up to 50 meters, and Miyota Cal.2085 movement.
Do note, you'll have to give the watch an initial charging during first use (just leaving it by the window while the sun is up should be enough). After that, it will pretty much just keep ticking unless you end up trapped in a cave with zero light for 120 days (it can run up to 3.5 months on a full charge with no light exposure), at which point, a non-functional watch is probably the least of your problems.
Available now, the Q&Q SmileSolar retails for $40.