Always be suspicious of advice from people who are trying to sell you things.  If you live in an area with reliable power, a conditioner isn't necessary.  I do believe in surge protection, however. You can get a perfectly adequate unit for less than $100 like the Tripplite mentioned in this site.  I've never seen anything from any manufacturer demanding a line conditioner, but the manager of the store that sells AV gear is going to push this stuff, as well as overpriced cables.