The only discounted late-entry passes that I know of are issued exclusively to convention-goers. If you are fortunate enough to be one, or traveling with one, there are "after 2 pm" passes. They are not park hoppers. They are $42 for a 1day/1park after 2 pass and $75 for a 2day/1park-per-day after 2 pass.
The sources that I know they are available thru are the Orlando/Orange County Convention Bureau and thru Disney themselves. Your convention organizers may also have a broker who will supply these passes. In all cases, you would need to supply the name of the convention that you are attending and may be asked to provide proof of attendance upon admission. If you are going directly thru Disney, the convention you are attending must be at one of Disney's facilities.