That's a really good question, they are hard to come buy without just buying a clunker for parts but get a matching model/type they are not all the same.
Watch gunbroker.com, I think gunsamerica.com also has parts maybe gunsinternational.com and auctionarms.com.
You might also try the forums on remingtonsociety.com
A Remington Mod 8 in 95% conditiion is about $500.00
Depends on (real) type and condition, condition, and condition. I assume you mean a double derringer (model 95)? Where did 1866 come from? A type I model 1 couldn't have a serial that high. (and that's the only one made in 1866) A type I model 2 doesn't have a serial no but a batch no A type II model 3 may or may not have a serial based on which variation it is but that's starting in 1888.
A Remington Model 760C in 95% condition would sell for around $375.00
Remington did not make a 44 cal double barrel pistol. The did however make a 41 cal (rimfire) the double derringer. (model 95) There's 3 type's, 5 models, and at least 15 variations some of which are quite valuable.
95% or better around 1200 to 1500
Remington didn't make a "1920's" handgun. The XP was a single shot bolt but not in 22, and the Model 51 was in 32 and 380, the Model 95 Derringer was still made but it was 41 rimfire. If it's a multi-barrel 22 with Remington on it it's a E. Remington and either a ZigZag (6 shot), Elliot (5 shot) or a single shot vest pistol, all of which are from the 1860-1870's. Also a Rolling Block Tartget 22 but wasn't made that late, last version was a 1901. I should add however, there are people who have made either the Model 4 or Model 6 into pistols they are also rolling blocks.
Which a single shot mississippi, split breach, vest, double derringer (model 95), caliber, variation? I'm suspecting your talking a double derringer 41 rimfire but that's likely not even a serial but a batch number. There's over a dozen variations with a HUGE range in value and even that's greatly dependent on condition.
$300 without a scope in 95% condition!!
The Davis D series derringer: MSRP - $95 $85 if in 100% (brand new) condition $40 if it is worn to about 60% condition
Remington NEVER made a two shot 22 pistol (6,5, and 1 shot), the only 2 shot they ever made was the model 95 (double derringer) and this was always in 41 rimfire, about 15 variations from 1865 all the way to early 1930's. There were foreign clones/copies made that actually even said Remington on the top but they are not. Really would need a photo to make any further identification.
yes. parts from a 93 to 97 model are mostly interchangable
87-95 engine parts should be almost completely the same. as far as body parts most of the line from 85-95. after that I'm not sure...