Good cheap tire patches can be made from small squares or rectangles of tevdek nonwoven paper, most commonly found as postal envelopes or house wrap. This is the stuff impossible to tear by hand. It can be glued in place with tire cement and will hold a tube very well. A tire patch over the hole will work also. With cuts up to 3/8 or so this will get you home with reduced pressure. If you are careful you can ride a road tire at 70-80# but watch the curves and holes. For smaller cuts, if the tire doesn't bulge you can just keep on using the tire.
Steve