Dwarven Ale

Is their a way to get drunk longer while saving gold?

Spiked Eggnog is the best overall.

You can get them for the same cost, or even cheaper, than DAle, and they last 3 minutes EACH.

and where can u buy them?

Spiked eggnogs were from the Wintersday event, only way to get it now is from other players. You could buy monastary credits, equipment requistions, luxon totems, and the imperial (something) from other players and trade them in for hunter's ale.

There's also that quest in prophecies pre-searing, where 5 drunk hunters will give you an ale for killing a bear.