I usually turn off the price on Amazon for one main reason. Sometimes the Amazon price is fine. At other times -- and without warning -- it will go up to a few hundred dollars for a simple product such as a paperback book. (I discovered this while writing for Squidoo.) This happens when Amazon runs out of the product and some individual or group is offering the second-hand product for an exorbitant amount. If I were a customer looking for that book (or whatever), I would be really put off by the advertised price. On the other hand, if, as the Wizzley author, I send that person to the Amazon site to see the current price, the customer can see for themselves the reason for the high price and can even order the item to be delivered when Amazon's stock is refurbished. The customer can also see some of the alternatives that are in stock.
Having said that, I have sometimes left the price on items in a couple of my wizzles. It is interesting to see what the response is with the different approaches. I would caution others, however, that if you leave the price on the item, you need to check your older wizzles regularly to be sure you are not turning potential customers away.
I leave the price on for eBay, as people often shop eBay looking for bargains, and the current bid is important information for anyone who is looking for something there.
Thanks for asking the question. I'll be interested to read other people's approaches.