Find a used one at salvage yard...Valves are not big selling items, thats why they are $$$$, on the other hand they don't sell good at salvage yard so you can probably find one for less than the customary 1_2 of new price..
By 'cracked' I take it to mean the seat is chippedIJ There are 3 items that can cause header leak down, your cracked seat, a faulty plastic poppet, and THE ORING AROUND THE CHECK VAlVE or a pirce of trash under the check valve. Email me , we might have a used one.
Who would have thought that International harvester also used Cessna valves on some of their combines, junk 303 that has been sitting on the farm for 10 years, donated a valve this morning and by 10:00am, I'm running. Thanks for the reply. Greg