Functionality of a form that receives bids for an item. What's best?

Question

I have a form that receives bids for items. It is shown below:

Image of the form http://yanma.com.ar/bid-taker-form.gif

In green you can see the price for the current winner bid, below, the minimum increase for the next bid (in the case of the image, the next bid must be $ 2510) and below the button to make a new bid. Next to this button (to its left) there is an input so that the user can enter the desired value to bid, since the bid may be higher than the current winner bid + increment.

My question is: Which is better from the standpoint of usability? It's better to have the input always default to the current bid value + increase and if the user wants to make a higher bid he changes the value? Or it's better that the input remains empty and the user makes the bid only pressing the green bid button to make the default next bid and enter the value in the field only if he wants a custom value?

Answer 1

My recommendation would be to pre-populate the field with the minimum next bid, but only if this is not the last step.

Take a look that this example from TradeMe (popular NZ auction site).

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The field is pre-populated with the next minimum bid. Placing the bid takes you to another screen where you are asked to confirm your bid, so there is little danger of accidentally buying something.

While there are two screens / clicks, the process is clear and easy. And chances are the user doesn't have to get anywhere near their keyboard.

Remember that more clicks isn't always a bad thing, as long as they are easy clicks (in case this was a concern :-)

Answer 2

I would pre-fill the textbox with the least amount someone can enter to bid. Or maybe make it a double option, see my attached image.

Wording and position of the elements may need to be changed according to design specs, but you get the idea I hope?