Hi
First ground rule, avoid purchasing second hand speakers as you may not know to what extent the user (owner) has driven them. Unless you know the owner personally, I guess then it is fine to take that risk to some extent.
Some technical aspects to consider about speakers is that the impedance should be the same or more than the amplifier. This means it should be rated at 6 ohms and above. Next is the sensitivity levels, minimum should be 85db...the higher it is the better it is for the amplifier to deliver clean power to the speakers which will perform at decent volume levels...Another aspect is wider the speaker cone, better the sound throw and frequencies emitted.....typical range is 20hz - 20khz and floor standing speakers perform at an average from 35/40hz to 18/20khz.
In my opinion, there are a lot of brands out there and which have difference in costs. For me after extensive use of various brands and models, the Boston Acoustics are true value for money. You may want to consider the A250 Floor Standers....these were once available for Rs 25k on HiFimart...just checked ..they are being sold for 32k now...strange...could be the Dollar vs Rupee conflict or the election results...check with other dealers if you can get it cheaper.....
ProFX has completed 10 years in India and are still offering discount in some locations, you may want to audition the Towers they sell and please take your AVR with you to check the tonal matching and performance....if the TSx series appeals to you, demand for a discount and they will render the same....atleast 10-18% for sure. The good part is that you get 3 years warranty......
All the best