The presenters don't control the price - they merely present. However, the producers, schedulers, planners etc., WILL know. It's their job to get the most for the piece they can and therefore even if it's lower on the CR website, they won't use that as a starting point - and why would they???? It makes absolutely no business sense to do so.
The price on the CR website will be above their cost price otherwise they'd go out of business. If they drop lower during an auction they'll be inching towards cost and that's not good for business. They have no obligation to bring the auction price lower than the CR price and I would think that they'll hope to sell for above if they can.
If that is their aim, then why bother having the auction site? People are going to buy items, see that they have paid more than they would had they ordered them off CR, return the items, feel cheated, and not order again. Surely that is not the companies aim?
They will have set their prices on CR far enough above cost to be able to go lower, or CR in itself would not be a viable business. Standard mark up in retail is at least 40-50%, so if they choose to auction a piece, there will be more than enough room to make us feel good by getting the piece at a lower price than we would have on CR, but is good for them as company, because they are still making a profit.
Some of the items they put into auction will be loss leaders, and as such no profit at all is expected. As well as that, there will be items that have been on CR for a while that they want to clear from stock to make space for the new stuff, which, I would imagine, will appear on CR before Rocks, and will be pieces that appear on Rocks if people request them, giving a price they will pay - as Steve was suggesting the other night.
There is therefore absolutely no reason at all why any item should sell above the price it would on CR.
To put this another way, if you looked in the Gems catalogue and saw an item could be purchased for, say £100, and it then appeared on the TV at a closing price of £150, with the over excited presenters telling you that they are cutting their own throats and cannot possibly go any lower. What would you think?