Twelveboar,
I don't know of a real bargain bowsaw but I do know that my 24 inch Jack bowsaw is as good today as when I bought it years ago. A little ridiculous I know because a bowsaw is only really as good as the blade but with a decent blade it has served me well.
Avoid anything with a Spear and Jackson label as you will wind up paying more just for the name but I would think if you spot a Jack or a Bahco (Sandvik as they used to be) you won't go far wrong.
Tack