You should check ebay, I was going to dump our 199C's on ebay until I saw the prices.. Broken ones barely fetching a hundred bucks sometimes
Indeed, probably the best & cheapest way to spare parts these days...
As for the prices, you can't complain that broken items sometimes sell for peanuts... typically, people using complex (more or less) test equipment will ALWAYS check whether they might attempt a repair or not... so items that land on Ebay are typically those that are deemed 'not easy to repair' (or 'not economically reasonable to repair'...) by their owner... I buy quite some broken scopes on Ebay, and I'm always completely astonished to see some people asking thousands of dollars for items that sell just slightly higher in working order...
Spare parts from the manufacturer are typically sold at totally indecent prices, when they are... most will require official servicing (and thus refuse to sell parts), with 150+ USD hourly price tag + mandatory calibration, and for many of the 'broken' or 'as is' scopes on Ebay, spare parts are unobtainium (even at the manufacturer)... There's a very, very significant (financial) risk associated with buying a non functional scope, and you won't typically be able to put that risk on the buyer...