Ok as i'm sure you all know there s a new patch coming out (1.12.1) that has a mount change making the lvl 40 mounts cost 10g and riding cost 90g and the lvl 60 mounts cost 100g and riding cost 900g.
Here the catch, if your level 40 and you havent bought your mount then get the mount riding whilst patc 1.12 is still out for 10g, then wait for 1.12.1 and pay 10g for the mount! I have not tested this out yet but im sure it would work, saved you 80g so i'd recomend trying it if you've just dinged 40.
anyway i hope it works :P