Try Midwest Gun Works
Without a detailed description of all markings, features, box, papers, accessories, etc.. you can be in the <100 USD to >1000 USD range.
Pretty certain you mean a Citori. If that is what you are looking at, it is a over/under trap gun.
Made in 1987, Browning doesnt list a Citori with a model 143 which is the last three numbers in your serial number. This is the model. They list a Citori hunting model as model # 153 however. As far as value, as with any firearm, it is not possible to accurately appraise a gun without seeing it. Condition, and original configuration will determine value. Other factors such as rarity of caliber or guage and higher grades have significant impact on value. Recommend that you see a local gun dealer for an appraisal. You can also do your own investigation by looking at other models being sold that are in the same condition as yours. Try the gunbroker.com or a periodical called "The Gun List" You can also reference the Blue Book of Gun Values which can be purchased on line at various retailers. Not quite. Browning does list a model 143 in the Citori line. 143 is the designation for a 12ga Trap model with Monte Carlo stock.
I bought a Citori Plus, in a combo set, which included a 34" trap barrel and the O/U barrel, plus the case. I bought it new about 8 years ago for $2400. I would think you could get around $1500 for the plus model, non combo set, if it is in very good condition, less if it has been "used".
Impossible to answer without an appraisal
You must add if this gun is a trap model,skeet model,standard model,golden clays model,sporting clays model before we can give you a correct price.Also include the condition of your browning as this will help quit a bit.
The prefix of 4M to your serial number indicates that you have a Browning standard weight model auto-5 shotgun,which was made in the year 1964.If it was a trap model,it would be so marked.
mfg in 1967
100-1000 usd
Need a detailed description of finish, condition, box, papers, all features and markings.
Please add the serial, but it is likely a single barrel trap gun such as the BT99