Re: model 788 barrel advice
Define affordable. Your desired standard of accuracy is important in this, as well. More than any other single factor, your desired level of accuracy will go a long way to determining price range.
Also, note that you do not need to look for a barrel that is specific to your rifle. Look for an unthreaded, unchambered, barrel blank in the contour, caliber, and twist rate you desire. Then take the barrel blank and your rifle to a competent gunsmith.
Expect to pay $200-$300 to have a good gunsmith do the install.