3240 is the module number, shared by other watches. Your watch looks like a Casio W800H-1AV.
http://www.casio-usa.com/products/Watches/Classic/W800H-1AV/
The second best seller on Amazon, a popular watch and it would help to know what feature(s) you want to upgrade. These are features people don't like:
- Acrylic crystal which is flush with the bezel (scratch magnet)
- No count down timer
- Buttons stick out
- Casio's strap, which is hard to replace
Some problems are not problems for everyone. For example, I don't mind acrylic crystals because the scratches are easily polished out. On the other hand, it's not something I want to do every day.
Two shot-in-the-dark recommendations for you.
Casio HDD600-1AV
http://www.casio-usa.com/products/Watches/Classic/HDD600-1AV/
Another $12$13 watch very similar to your watch. The buttons don't stick out. The acrylic crystal is recessed under the plastic bezel, giving it a little scatch protection. According to Casio, it is 1.5mm thinner than your watch. Main time display shows the date and day of the week but not the year.
Casio Wave Ceptor WV59A-1AV
http://www.casio-usa.com/products/Watches/wave_ceptor/WV59A-1AV/
This watch, still in Casio's USA catalog, has been discontinued here. It is still sold in Europe and Japan, and Amazon sells the Japanese market
Casio Wave Ceptor WV-59J-1AJF for $50. It sets time and date every night from a radio signal broadcast from Fort Collins in Colorado, Anthorn in the UK, Mainflingen in Germany, and Mount Otakadoya and Mount Hagane in Japan. Otherwise its features and size are similar to your watch. Water resistance is 50M instead of 100M: wear it in a driving rain but not swimming. Crystal is mineral glass which is more scratch resistant than acrylic, but it's a domed crystal which looks sharp but is more easily dinged. This older model Wave Ceptor cannot receive the time setting signal broadcast from Shangqiu, China: a deal breaker if you live in China, Korea or Taiwan.