I am a fairly regular online shopper owing to long hours and unlimited net connection at work :). Over the past year, I have made around 6 purchases at a total value of Rs.20000 on e-bay india. Every single purchase has arrived on time and in good condition and has worked well. Sellers have also always been responsive to all queries.
*Sections where I can recommend purchase
*Sections which I regularly purchase from are mobile phone accessories, computer accessories. I have noticed that these items are reasonably priced and delivered promptly. Maybe, you will get a cheaper deal somewhere in the markets of your city, but its not always possible to go there everytime you need a small thing! In all of these items also, prices (and shipping prices) and even brands and specs vary widely and very often, it is the smaller sellers who are giving better deals. So do interact with them and check out how reliable they seem before going ahead.
I also bought my MP3 player off e-bay and I would recommend to check out models of Creative, Iriver etc. there - some of these are not so readily available outside.
I also recommend that its best to buy from sellers who offer reasonable buy it now prices rather than those who constantly run auctions. I find auctions gimmicky and I dont understand them too well, so I avoid such purchasing. Besides, I never really need the stuff thats on auction!
*Sections where I recommend you check outside prices
*Mobile phones, furniture and home appliances - you will get better deals in shops outside.
*Watch out
*If you make a purchase of above Rs 10000 on your credit card, they require you to fax a copy of your card to them for verification. This upset me a bit as I feel it opens scope for card misuse.
On one occasion, I had used my card and then the purchase got cancelled. I had to interact with e-bay customer service and I found them to be prompt and responsive, both on phone and e-mail. The card charges were reversed within 48 hours.