I dun think there will be anyone who wants to buy the 820 nowadays (and not many shops will stock in that). 820 & 720, maybe more RAM, but 720 has big battery. I personally prefer more RAM, but I actually see more people using 720 than 820, maybe because 720 is newer. These 2 are pretty much cannibalizing each other's sales.
720 & 625 are pretty new so price doesnt drop much. I also have a 520, and this little phone is awesome for RM 500 price.
For 1320 i expect a RM 1199 price tag, approximately. USD to RM is now RM 3.2X to RM 3.30. but, dun forget, 1320 will be released in Q1 2014, and that's in western countries and selected asian countries (not necessarily Malaysia), but 1520 will be out n Q4 this year. before we get the 1320 early next year 920 and 920's price will remain "high" for a while. 1320 is damn cheap when compared to galaxy Mega.
Some ppl prefer smaller phones, i hope Nokia slot in a high spec phone (like, snapdragon 600 at least, with 2GB RAM, 4.3" 720p screen) in the 8XX series next year. Sony has the Xperia Z1S,. which is still unannounced (officially as Z1F in Japan) which has this kind of spec - complete with 20MP cam & Snapdragon 800.