Highly desirable Stevens model. Edit: I missed the "044" there, it's different from the 44-1/2; but still desirable. Yes, condition is everything but these will command a premium in any market. I can't recall whether .25-21 Stevens is the same as .25-21 Single Shot, the latter of which is available formed but yes, as noted above, it is PRI$EY. Regardless, it is indeed possible to make your own (OK, shortened - but functional) .25-21 Stevens from donor brass if you have a lathe, the right series of dies and and patience.
As stated above, pictures are needed.