It is a marketing gimmick. If you have to email to ask, then they can start conversation with you or get you on the phone to talk. Same reason you can look at your local paper and see all the ads for the local car lots and prices are not always listed, just options and incentives. I personally always try to post my prices in my ads. I don't want to waste your time or mine.
Why don't people post the asking price for their car's when trying to sell? If you are going to post 4 sale or trade post a price.
No price then they usually want too much. We have between 6 and 20 ads on here all the time all have prices and descriptions but some of the off the wall questions we still get must be coming from 10 yr olds because grownups could not be that syupid...are they? Some people just like to talk on the phone or type emails. Good post,was needed