I replaced one of my fuel bladders in 1988.
I got it from Continental Fuel Cell Repair Co.
The other bladder is still working just fine.
The bladder I removed was not repairable due to
the material it was made of.  The newer ones are
repairable.  Hopefully you'll be fortunate enough to
have one that's repairable.
I have no idea as to the cost of labor, as I spent
the best part of a weekend laying on top of the plane
getting the old one out and putting the new one in.
I did almost all of the physical work myself as my
mechanic watched.
The bladder is going to roll up and go into the hole
your fuel cap is in.  Warming up in the sun will make it
more pliable.  There are snaps inside the wing
and on the upper outside of the bladder to hold it
into place.  Most of the job will be done by braille.
As I recall, there are two flange rings that will be attached
to the bladder, where the fuel cap goes.  That flange is
held in place by that circle of screws around your fuel cap.
The flange rings from your old bladder might be worth
a few $$$ if you send them back to the company.  I think mine
got me $25.
A long skinny arm is real handy, as you have to reach through
the hole to position the bladder.Also, I believe there was a loop inside the bladder to hold the vent tube in place.  Make sure the tube is properly placed so it can do it's job.

Solid tanks can be put in.  They have less problems but
cost more to buy and more labot to put in.  The wing has to have sheet metalremoved to put them in, then have the sheet metal replaced. I think that comes under major alteration.

I'm pretty comfortable with the "issues" of the bladder tanks
and didn't feel it necessary to put in the other type of tank.

I'm sure one of the fine mechanics on this forum can give you
a ballpark estimate on installation.

Michael
(too bad duct tape isnt fuel proof)

   Mike and Glen , Both answers were very helpfull . Some of the
  best people are in aviation ......thanks again .....Nick