I did a round butt on my Loaded project, then went onto a
bob-tail. Cost was about $100, not counting sandpaper &
refinishing. Took about four hours, only special tools needed
are the jig from Ed Brown, drill press and an anti walk drill bit.
Jig & bit are available at Brownells.
Below is a link to the pics i took while doing this. The Springer
is currently at a shop getting refinished.
pics are in reverse order, take a look at page 2 first.
Link for the round butt,
Link for the bob-tail,