500 or so
A Franchi Spas 5 shot semi auto needs a firearm certificate, (section one certificate) converted to a 3 shot only needs a shotgun certificate (section two certificate Franchi Spas are a great trouble free gun or try the Raptor gas operated Franchi
If you're looking for a magazine fed semi auto shotgun without spending an arm and a leg for it, the obvious choice is Saiga. You could get a shotgun, send it in to have it optimised for low brass rounds, and get a 30 round drum for about $1500.
Depending on condition,your browning auto-5 shotgun is valued at between 425-725 dollars.
A Franchi SPAS-12 Shotgun has both a pump-action and semi-automatic mode. Automatic in shotguns will generally reference semi-auto unless stated as fully automatic.
around 450.00
50-175 USD
Generally, between $450 and $550. This quality semi-auto shotgun is available with both wood and synthetic stocks and price may vary with condition and type. Barrels are available in 18", 20", 24", 26"and 28" lengths.
0-550 usd
Model 24 is a semi-auto 22.
50-460 USD or so
depending on the condition of your browning auto-5 shotgun,these are valued at between 300-600 dollars.