hey there, im also in india and getting myself a desire hd soon.
buy the sim free/factory unlocked version from uk and it will work.
it is launching in india(and the rest of asia) sometime in november, but you never know how much they delay it because there is already too less stock for the europe.
initially it will only be available with vodafone but later it will come unlocked and with other carriers too.
vodafone is expected to offer 2gb/month free usage for 6 months with it. you can avail this offer even if you bring an unlocked version from the uk as to avail this offer you only have to send an sms from your desire hd.
the price will be about 29k rupees for the desire hd and 27k rupees for desire z.
some good websites to get desire hd to india are expansys.com, handtec.co.uk.
on both the websites you can buy the phone for about 435gbp including 3-5 day shipping to india by dhl/fedex/ups.
on handtec, you can also choose to save about 20gbp if you choose royal mail which takes 10-12 days to deliver once shipped.
about the customs duty, dont worry much, if you order by royal mail you wont have to pay a single rupee for the duty or tax and if you order by dhl etc. you will end up paying hardly 2k-2.5k rupees for duty. mobile phones for non commercial usage are greatly discounted from customs as such you may end up paying zero duty even by courier.
im getting the phone from handtec and choosing courier shipping.