One caution: SPAM isn't actually cheaper than ham, it's just shelf stable without refrigeration. You can get a decent spiral ham for well under $3.29/lb (Costco earlier today), but 12oz cans of SPAM work out to around $5/lb.
Of course one could argue there's an even higher percentage of inedible parts in the canned monstrosity because it's all inedible, and I wouldn't argue that view point is wrong.
Hams like that often go on sale around US Thanksgiving and Christmas, with prices for them around US$4.50-6.50/kg last week and probably as 'loss leaders' around US$2-3/kg the week before Christmas. Ham is a regular part of 'traditional Thanksgiving' but not as much as turkey, whereas the 'Christmas ham' is definitely a thing.