Modifying a 12 G.Bbl.for choke tubes

[BWANA]

I want to have a Remington 12 Gauge 20"cyl/bore Bbl modified to take screw chokes.
Where's the most reasonably priced place to have it done ?
What's a fair price ?

Thanks,

 

[Papaneil]

Well, I do it for $120, plus chokes.