Not really more cost effective, but then again, I guess that depends on your goals. I havent used exemestane or letrozole yet, but I plan on using letrozole next cycle. Now, I am looking at underground prices of $3 per 1mg anastrozole tab and $3.50 per 2.5mg letrozole tab. 50 cents per tab over the course of the cycle may be a bit much, but at the same time, the added increase in IGF-1 caused by letrozole may be worth it. Exemestane on the other hand is $5 per tab via the underground and at present may not be worth it unless your on a massive cycle and need all the protection you can get. I guess time will tell.