Affordable does not means good. For malaysian market, pristin.
If you can get access to fish oil sold in US, Nordic Naturals is the best but it will burn a hole in your pocket.  For those who bothers about money, Carlson very finest liquid fish oil.
The 2 brand I mentioned above are
(i) have high EPA-DHA ratio (which means take once a day is enough + lesser amount to consume)
(ii) certified by IFOS that the fish oil is free of contamination/pollutants, fresh (very important factor!), meets the label description.
(iii) triglycerides form (personal preference-absorb better, less prone to oxidation compare to ethyl ester oil-most oil on the market are ethyl ester which are cheaper to produce)

Something to look into when buying fish oil
http://www.smh.com.au/lifestyle/diet-and-f...120-12uof5.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300506/

This is exactly why I choose IFOS certified fish oil. With IFOS, the manufacturer cannot lie about their products and the consumer have a 3rd party vetification.

I don't know about low blood pressure situation. But I am student with normal blood prrssure and I take 1 capsule of Nordic a day and so far, my blood pressure have never drop.