Loving Greg's idea. I also hear that if you freeze the grapes on the stems, they are easier to remove. Combining the two might be worth pursuing.
I have also heard you can freeze grapes and run them through a crusher set loose and the grapes will come off the stems. Then you pluck the stems out. Never have done either, but looking for a faster way than hand picking.
Used wine equipment never comes up on CL or classifieds here. Maybe a carboy or two, but even those are priced near new. A new manual crusher destemmer is $400 plus shipping.
For 25 gallons a year, it not worth the cost IMHO. I make way more than that and I still do it all by hand.
BTW, if you use wood to crush, be sure it is not treated lumber.