you would need to use the set session value from either ecart or cookies toolkit for this to capture the form post value into a session.
Open the server behaviors panel and click the plus button.
If you have eCart go to eCart -> General -> Set Session value
if you have cookies toolkit go to WA Cookies Toolkit -> Set Session Value
Set the trigger to any form post, set the name to maxPrice
Click the lightning bolt next to value and select the maxPrice form element.
now, create the message:
There are currently 4 offers up to £
then drag the maxPrice session from the bindings panel after the £
Add the same if statement around this message as is around the link.