It's more costly because this is a true apochromatic triplet where as the Orion 80ED is a basic doublet. In that respect the lens isn't so expensive. The scope that normally carries that lens cell would be around another 250 euros.
I’say that your best bet would be to search astronomy forums and classifieds..Astromart is the USA main astronomy marketplace,with a dedicated classifieds page ,and you can find anything really..It is US based but there are members from all over the world..shipping the cell shall not be a fortune anyway,and if you place an add you might get lucky and get an offer from Asia ... there is a fee ,though,to become a member and use the classifieds,but then again,might be worth it..another popular site is Cloudy Nights.I am sure you will find similar sites in India
I think you will struggle to find the type of lens you are after and then build a scope cheaper than just buying an Orion 80ED. I've had a good look around the web and couldn't turn up anything much. There's plenty of good ED lens cells but they cost a lot.
The only cheap ED one I found is here but it's 70mm and 420mm focal length. You could use it for photography but the focal length would require you to get closer to the subject. It only costs 199 euros
Intane Optics used to sell lens cells but their website has much less info now than it did a few years back. Might be worth emailing them just too see if they have anything to sell you. They used to make some cheap scopes using their own lens cells but they seem to be discontinued now.
Parivel, I searched and searched, and emailed and emailed for exactly what you are looking for. I searched forums, endless optics providers ect. and wasted more time than I care to admit. I found nothing with anywhere near the bang for the buck as the 80ed doublet complete scopes (although there is the barska 80 fpl-51 triplet). If you find something, please let us know, but my advice for a cheap objective lens is finding a used 80 fpl-53 doublet complete scope. I picked up mine for $250 (US dollars). Someday I might buy a TS optics 90mm objective, but for saving money, it really doesn't look like buying the objective is the cheapest route until you are buying something much higher end, and even then it appears to be about a 30% savings and very rare used.