I have used the mechanical Radio Shack one on numerous occasions and have never been dissatisfied. They also have a remote controlled one too now, and we used it for a week on a Mit 73905, again no problems at all.
Start with the simple mechanical one and go from there. The internal shielding is first rate - whoever RS gets theirs from is probably the same supplier of the much more expensive ones, and identical in every way. I once had to replace a horn tweeter in an Altec Lansing speaker and when I got Altec on the phone they told me to go to RS because it would be exactly the same tweeter because of their getting it from the same source thing.