Well, it sort of looks like a 1924-ish TB 1, sort of. Here is a link to Greg Earnest's website with many photos of old Gibsons.

earnestbanjo.com/wp/gibson-pb-1-11055a-31/

The peghead and tan finish on the neck with extended fingerboard look very similar. However your photo shows the Pyralin plastic resonator. The one on Earnest's website shows the more familiar wooden "Trap Door" back on the banjo. His website doesn't seem to have any photos of early 1920s models with the Pyralin resonator, but I have seen such photos elsewhere.

In any case, these are not particularly highly valued. Your photo looks "playable". If that is so perhaps a value up to $1000 just due to its age and scarcity -- however it's not a popular type of banjo in today's tenor banjo community. But I'm not expert on these early early Gibsons. If it's playable, not needing repairs and you like it at the asking price, then for you it's "good". I don't know what kind of music you intend to play, but 1920s Vega tenors are much easier to find in the market, and most of them are $1000 or under.

It's OK to replace the strings right now before you buy it, if the seller agrees. Otherwise, if you buy it, of course you can strings at will.

My question is, what about this banjo makes it attractive to you? Are you in an area where tenor banjos seldom come up for sale? A USA buyer probably would pass on this banjo unless it's REALLY inexpensive.

I'd call it more of a curiosity than a desirable tenor banjo.

Many Thanks for you reply,
I wanted to play New Orleans, do you think it will be suitable ?
Is there any other brand and model i should try to find ? i am in France...
thanks a lot !

Not suitable for your needs. It’s a plectrum and you want a tenor. Further,it’s likely too quiet for being heard in a NO-style band. I would think you want a banjo with a mastertone-style ring (if Gibson type). A Vega Tubaphone with resonator or a Silver Bell would also be suitable.