I designed the 1210-X, it was a good machine for its time and price tag but that was nearly 30 years ago. A hundred bucks is too high a price for a used 1210-X, it's not a "collectible classic" and won't likely ever be.
For about that same price you can get a brand new Bounty Hunter in several different flavors. Depth will be about the same (on the order of half a foot on coins) but the features and responses will be better. And some of 'em are so ugly that you could probably leave one on a park bench overnight and nobody would steal it. (That's what I liked about my old beat up Honda Civic but someone stole it anyhow.) You might like the BH Tracker 4 (TK4), inexpensive and ugly but it's almost impossible to find an unhappy customer. The boss won't let me redesign it, he says it ain't broke and he doesn't want it fixed. We've got others in roughly that same price range too, if the TK4 isn't quite what you want.
Some people do very well with inexpensive machines that don't have a lot of hots -- after all, if you're into public parks and tot-lotting, you darn well better not be bringing a shovel along with you. The Compadre is good for that kind of service, it may not be our product but I ain't gonna knock it. However, if you do much beeping in situations where depth is important, you're gonna have to spend more. And you'll get more features whether you wanted them or not. When you've got those features, you'll learn to appreciate at least some of them. Many people regard our Fisher F2 and Teknetics Delta (in roughly the $200-350 price range depending on what package you get from whom) as offering exceptional value with performance only a little below the big leagues.
And regarding that other question you had, the 1210-X searchcoil won't work on a Compadre, sorry.
--Dave J.
PS: for those who may not know: Fisher, Teknetics, and Bounty Hunter all come from the same company here in El Paso, that's why I can get away with pitching several different brands on a Fisher forum. Night Owl and iGen hand-held night vision products are also ours.