Yep that's kinda confusing to me too because usually security deposit was first collected when you received a modem on RENTAL from BSNL without shelling the full cash, whereas I think, or rather, they are asking you to BUY the modem from them no, then why deposit?! Trust me bro, BSNL and Bills and Cash/Refunds are a real mix up sometimes. Is this a new connection? If it is, then they WILL somehow get that 500 in as some cost (Registration/Installation) as I mentioned, if not immediately, then in the first bill.Be very careful with BSNL's wordings and ads! They'll have big posters of NO REGISTRATION, NO INSTALLATION CHARGES! Then say no that meant not immediately payable, but payable in FIRST BILL! Dafuq?! Later, bills usually only come with Broadband Charges, Call Charges and Tax since no modem rental when you get your own modem!I have got an EVDO modem from them first when it came out and they had the cost mentioned as 2100 whereas they collected 3500, yes with the Rs 2100 poster right behind them! Plus the first bill came with 1k more quoting deposit and installation charges! Installation Charges of WHAT?! Best part is they had a big arse 3G icon on the EVDO box, but later on down the line you come to know that it is NOT and they wouldn't exchange it either!
For my modem part when I was taking my connection BSNL had offer as, you pay security deposit and pay rental, and if you use for more than a year the modem becomes yours and the rental turns into discounted in bill. Whereas the modem became defective, they REFUSED to give replacement stating NO STOCK. I returned the modem and DID NOT RECEIVE the Deposit to date! So they can sometimes really get on your freakin' nerves!Not sure of any link with cheaper price, but then did you try your local electronics market and see if it is cheaper than the price quoted by FK? For the repeater mode not a big deal about the WPS button, since the modem/
router login pages will have settings to choose the same, I think along the lines of Bridge mode or Repeater mode. Search around for links on how to do so bro, or probably the manual itself might have them. I am sure there are some tutorials around, probably even on youtube. Sorry if I ain't being helpful enough.
All the Best on your hunt and hope your setup is not a PITA and wish you smooth sailing/surfing ahead. Cheers and Take Care.