Could be worth alot could be worth very little. If you can get it for $300 to $350 and it looks OK to you go for it, otherwise do your homework first. On the internet try:
The U.S. Springfield Trapdoor Rifle Information Center and post a detailed description. If you have time buy Poyer's book on the 45/70 rifle.
Things that matter:
- Date, S/N, any marking on the metal or wood
- Length of barrel and number of bands
- Broken parts
- Cartouche (if any and quality)
- Length of barrel (many have been shortened)
- Are the screws buggered up
- Missing parts
- Quality of the bore
- Original stock? (many carbines are shortened full length stocks) (see if the ram rod hole has been plugged and sanded) carbines don't have ram rods.
- If a carbine, does it have carbine sights? Should have a "C" stamped on side and not a "R"
- Front sight original?
- Saddle ring present/original
- Can you reand the "V" and "P" on the barrel?
- Extractor works and spring present?
- Has the stock been sanded?
- Does the S/N match the year on the breech block?
- Does the lock work properly?
Good Luck!