depends on what you want. if you just want the perfume itself, go off retail.
but if you don't mind adding in like 30 or so bucks, you might get yourself some nice gift sets. gifts sets come with other gifts like I got myself a Bvlgari Aqva's shower gel, 100ml EDT, and a toiletries bag all for only RM 250 once from Isetan. that's a bargain.
for such offer, you really have to be thick skinned by keep checking out the perfume booths in department stores. I even got myself Jean Paul Gaultier's Le Male 125ml for RM  199 in December 2011. came along with some free samples.
but keep yourself noted that Chanel & Dior don't tend to bargain off their fragrance. so, if you can find a genuine/ authentic seller that supplies Dior/ Chanel that sells them at a lower price, go get 'em.
for Chanel, usually they give freebies for purchases of RM 500 and up (for a miniature. 30ml or so). but if you spend RM  800 and up, they give you a bag. toiletries bag or a makeup bag, I can't recall. but for such offer to be available, you have to wait for them to open up a promo/ offer booth. so yea.

you gotta know your stuff when to strike and where to strike.

p/s: Davidoff Cool Water is love. my 1st scent. chick lover. compliment getter!