Actually, the IH 295 planter units were first produced starting in January of 1969 and continued to be in production for quit some time. Some small changes were made throughout their production years. Most if not nearly all were double disc opener type units and will plant many thousand acres without major investment for parts. The bearings in the double disc openers will eventually fail but can be replaced without buying the whole disc if you remove six rivets.
The JD 71 flex units were much more popular, but, I preferred the IH 295. Most sellers on the net seem to want about $295 for each unit. I'm sorry but I don't know their original cost. At $295 they better be pristine, notably no cracks in the casting members, the fiberglass buckets in good condition, gears not excessively worn (there should not be too much play), lids fit well and are not cracked, double disc diameter large enough to plant at correct depth, are the seed tube in good condition, etc. Depending on the crop you want to plant, do they have the correct depth bands?
If they are in good condition they will do a very good job at a reasonable cost.
Quit a few sellers of seed plates (mostly used) are on the net. If you need new plates they can be obtained from:
Lincoln Ag Products
They are located in Lincoln, NE. I am located in the same state but am near Wyoming in the Panhandle. Plates are not cheap, but neither are the JD plates.
Good luck,