I have been using reliance data card for almost a year now and its doing the job.
All the mobile wireless connections at present are only good for checking e-mails and stuff and are very slow except for bsnl evdo data card which will give you 2.2mbps speed and I think its 500-600 rs a month or something like that for unlimited usage.. but you have to make sure your local bsnl towers are evdo enabled and also check if someone around you is getting good speeds on bsnl evdo or not coz if evdo is not enabled then it would be very slow speed like every other data card.

I have heard that some mobile operators will launch 3g in january so I suppose things will get better in the near future.