LWT's... I love LWT's... It was my very first gun. The Commanders were first produced in the late 40's thankfully, as there are a few floating around that qualify as C&R's for sales in the PRK, although they are rare, and pricey.
Most likely, that one has the roll mark I like, small letters, little pony, yadda, yadda...
$550 is a great price, but don't be surpised if you are buying someone elses nightmare, and need to spend some more to get it running good. Of course, in CA, an S70 Colt is only legal for transfer through Private Sale (through the FFL). See if you can talk with the owner of the gun.
Also, the "Barely Shot" description is often one that comes out "Shot to Sh1t" Again, see if you can speak with the former owner.
It's hard to tell a gun that has 100 rounds from one that has 3000 rounds, if the person took great care of the weapon. My "caution Flag" always goes up on Used Guns when I hear "Less than 200 or 500 rounds" through it, kinda that "Little Ole Lady from Altadena" thing
Bottom line, enjoy the new baby when you finally pick it up next weekend. Give it a good once over before you shoot her. Since she is an Alloy, ensure that the rails are well lubed, and double check the ramp for gouges, if the former owner shot lots of JHP's through it, you may see some scar's.
I am guessing that since it's wearing Ivories, it's probably a Satin Nickle finish. Check the finish really closely, and chek the rails. Finally, check the staking on the front post. You may want to have a dovetailed one installed, but I have had a few staked on posts that popped off.
FWIW, enjoy your new baby... I am hoping to find an early 38 Super, preferably a LWT, but a Steel frame would be fine, to add to the Enhance S80's LWT I have now.