You first need to decide whether you want to shoot smokeless powder or black powder.
You are not going to buy a very good quality Sharps for $1,000. You may find a decent used one, but not a new one.
If $1,000 is your limit then I would search for a good used 1885 HighWall rifle. You should be able to find a 45-70 in a good quality HighWall for that price if you take your time. Tom.