Send it to CAS at www.cylindersmith.com. I just got my Blackhawk Convertible cylinders back and he does an excellent job at a reasonable price.
If you are just doing a few cylinders, it's not very economical to buy the reamer and accessories and then just have them laying around.
I guess if one was going to do a number of gun it might be worth buying the reamer. For me, it was less trouble to send them to cas at Cylindersmith who did the cylinders on two .45 Blackhawks and also the the extra .45ACP on my convertible. Turnaround was quick and the guns do shoot better. I'm right happy with the results.
In the classified section there is a thread where a reamer set is making the rounds, and it will cost you about $5.00 out of pocket, and you do it yourself. It is very easy to do (not much harder than removing a clylinder from a SA), and takes less than a half hour. When your name comes up, you mail the deposit funds to the person who is holding it, and they mail it to you.
Thanks fellas for all the replies. Since I missed the reamer while it was in MI, and I need to get my cylinder done ASAP, I'll will send it out to Cylindersmith. I only have one cylinder to do, so spending $100. on tools is out of the queston.