Traditions made 2 striker fired inline 12 gauge shotguns
that were named the Buckhunter that uses a #11 cap
and the Buckhunter Pro that uses a 209 primer. These
discontinued shotguns are drilled & tapped for mounting
a scope and the muzzle has internal threads for using
Mossberg Accu-choke choke tubes.
I have the Buckhunter that uses #11 caps and it looks just
like the current Traditions Tracker 209 inline except it only
has a bead front sight.
A used one was being auction on Gunbroker for $189:
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=224050247
Another similar inline shotgun is the Navy Arms Country
Boy 12 gauge that uses a #11 cap. It was made in China
and has a permanent Poly-Choke device attached.
That consists of metal fingers that slightly open and close
to control the shot pattern, and which makes it a little more
difficult to clean.
whosyrdaddy offered his for sale for $125 or trade:
https://www.thehighroad.org/showthread.php?p=5381786
One may also be available for trade on Armsbid:
http://www.armslist.com/posts/90212...ers-for-trade-navy-arms-muzzle-loader-shotgun
There's also inexpensive used sidelock shotguns. For instance
I have an older Spanish 28 gauge with a modified fixed choke
that I've seen listed on Gunbroker for ~$150. It can handle full
house 12 ga. loads of bird shot and will also accurately shoot
.520 patched round balls at short range. It also has a grooved
rear sight and these were sold by Dixie Arms about 25 years ago.