Is it best to have a Lexus dealership align a Lexus or does it matter who?

I own an 01 ES300 which I just had Sam's put new tires on, so I'm obviously shopping around for alignment. First call was my local Lexus dealership who wants $175 and only performs the service on Fridays (price is acceptable, but Friday doesn't work for my schedule). The car isn't under warranty, obviously, and I have several friends telling me $175 is way too overpriced for an alignment job and it doesn't matter who does the alignment on it because anyone can do an alignment on any car. However, I have a couple of friends who are Lexus owners and they say that for computerized alignment services I should definitely take the car to noneother than Lexus, as they are the only ones able to do it to the correct specifications. Is this true? Does it take a Lexus certified mechanic to correctly perform an alignment on the car or could I take it to another party?