The decision to bore or not to bore should be made based on the condition of the cylinder,(ring ridge,taper,out of round,scoring) and not on finances.
If the engine was a low milage engine with NO wear, then you could get by without boring. Especially if you plan to run forged pistons. Since they require more piston to cyl wall clearance. In either case I would still recomend using a rigid hone.
If the cylinders have ANY wear, you would be better off putting in a good running used engine to get by until you have the cash to do a proper rebuild. Then sell the used engine to someone else in the same boat when you`re finished.