If yours is a two shot derringer, value is ABOUT $200. These were only made 1972-1974, so it is difficult to find a recent sale for comparison. References do list it as a "Well made firearm".
Need the serial number.
No published sn data. You will have to call Rossi
Depending on blued or stainless.....anywhere from 260-320 brand new. Used i assume would be less than that.
Take it to a firearms dealer or appraiser. There are also plenty of books on antique firearms at your local library.
this question should be under Colt Firearms section
Winchester did not make firearms in Belgium
Not all makes of firearms HAVE a model number. Some makers use model NAMES (um... like Bulldog or Undercover, or Undercoverette) instead of a model number.
The phone number of the National Firearms Museum is: 703-267-1600.
Ithaca Firearms manufactured the Lefever Nitro Special after it purchased Lefever Arms Co. in 1916. This model was made between 1921 and 1947; the serial number indicates yours was made in 1929.
Ithaca Firearms manufactured the Lefever Nitro Special shotgun with serial numbers between 101600 and 119899 in 1922.
All stainless is not created equal. For surgical-quality stainless least likely to rust, get 18/10 stainlees steel. A lower number before the 10 is lower quality .
Classic firearms can be purchased from a number of locations. These include online at Classic Firearms or Firearms Thinkers. One can also find listings for collectible guns on sites such as Craigslist, eBay, or even in the local newspaper.