Dont bother getting a stabilizer. Just a 1kVA+ UPS can do. However I would strongly recommend you NOT to go with APC as it gives noisy square wave output when running on batteries. Better go for Microtek or a home UPS (cost will be very high due to high capacity external batteries buy you could use it for your entire household).
Only if you go for a Home UPS, a Stabilizer will be needed.
Going for a home UPS will be expensive then have to buy stabiliser too in that case.
So according to u microtek ups will be better than APC ups . So u think 1KVA should be sufficient for running 50'Plasma tv, HD box, media player.