I believe Crosman never made a model B661 (But I may be wrong) I've searched the web and 5 different Catalogue Airgun books and can not find any reference to a Crosman Model B661.
there are over 100 different model Crosman airguns. You need to specify the model and the condition of the Crosman you want to know about
Between $125 - $165.
I have absolutely no information on a Crosman model 143. Are you sure it isn't a model 140 or model 147. I even searched the net and can not find anything on a model 143.
What model is it. How old is it, what condition is it in, is it still working?
The Crosman model 454 was made between 1977-1982, in two variations it was modeled after the Colt Woodsman. It is a 16 shot BB C02 pistol. It good condition it is worth between $25 - $30.
The Crosman model 160 was made between 1955-71. In mint condition (Very unusual) it is worth between $190 & $225 add 20% for factory box. There were 3 variations of this model.
I can not find a CROSMAN model 350 BB gun, Do you mean a V350 BB rifle. If so then one in good condition is worth between $55-$70
This model was made between 1964 - 1985 in 3 variations. Today in fair condition it is worth between $25 to $40
The 1924 was the second rifle model made by Crosman. It was the first Crosman underlever model made, before that it was the 1923 model that had a plunger pump under the barrel. Your model was made between 1923 -24 and in Good condition it is worth between $1,450 to $1,875. Source Blue book of airguns 10 edition
This air rifle was made for Montgomery Wards under the Revelation brand name by Crosman. It truth it is a Crosman model 760 First variation. 1966-1970 Average price in good condition is $15.
Crosman has made over 100 different models of air rifles and guns. If you want an estimate of value it would help if you identified the model.
What is your Question? Are you asking about a CROSMAN model 120 price or problem? Please re-post