Yes, gurnani, we understand. When you purchased those apps from a third party, you were actually aiding that third party - and you - to commit piracy! That businessman was making money by re-selling apps he bought from the App Store. Who knows how many times he's re-sold those apps (that he only bought once ... if at all). All those resells represent money that does not go to the developer/owner of the app.
To give you the benefit of the doubt that you didn't know this was illegal behavior, and to help others who may be faced with the same situation:
Applications for an iDevice can only be legally purchased at the App Store. If you buy from a 3d party, whether in a physical store or online somewhere on the web, you are participating in theft and piracy.
The best thing you can do is to forget whatever money and time you've got invested in those apps and go ahead and upgrade your iPad. Then, should you want those apps back, go to the App Store (either via iTunes or on your iPad) and buy them - legally this time. Then, you will have legal purchases that you can always update (and you won't have to worry about firmware upgrades, either.
I'm sorry that you got caught up in this. Please, take it as a lesson learned and delete those apps so you won't be a part of any piracy schemes. And, tell your friends and acquaintances to avoid that "business." Because, now that you know - you sure don't want to be a pirate, right!?
Marilyn