There are always a bunch of Gralab 300 timers available on Ebay. Several have sold recently for $30 or so, although others have gone for much higher. This is what you're familiar with, and although they seem to just run forever, if you had a second one on the developing side you'd have a spare in case your enlarger timer ever gave up.(posted 8241 days ago)The Gralab 300 is what I use on the wet side of my darkroom - actually two of them. One was my father's, which must be 50+ years old and has the bell (single ring at the end of the time - fairly loud, but then it's over) while the other one is the new model with the adjustable volume buzzer. I have one at the middle of the wet side where the paper developing tray usually sits, the other is at the sink where it's easier to set and see for developing film.
I actually prefer the bell model with its single ding, because the buzzer model just goes on and on, and even at its lowest setting is quite annoying if it goes on for any length of time. Sometimes I'm doing something else when the buzzer goes off - like framing and focusing a negative in the enlarger - and it isn't critical that I do something at the end of the time - like take a print out of the wash. I just want to know when the wash time is up, and a single bell is enough. The operating advantage of the bell model is that I can leave it "on" all the time and just click the minute hand over two minutes at the start of a print, which starts the timer running immediately. Then, if I want a bell to ring at the end, I just tap the bell button on the top (which I think cocks the bell mechanically) at any point before the time runs out. At the end of the time the bell goes off and the timer just sits, waiting to run again. With the buzzer model I'd have to set the minute hand then flip the timer switch to on, and I have to turn it off at the end in order to silence the buzzer.
On the whole, I find the bell model friendlier for paper timing. But the bell models are quite old, and I don't see them very often on Ebay (not that I look that hard for them, though.)