I think you could get by on a Mage without spending 5 - 10k... Maybe more like 3 or 4.
Magicians are expensive because they are great solo characters and decent cata chars as well.
If you really want to go Mage, I would focus on getting a decent set of heal mastery gear and heal charms and then you would be appreciated all the way up in catacombs. That way, you can just heal for a few climbs to build up stat points and hopefully get a good drop or two

then once you can afford attack charms and int gear you can start casting solo or whatever.
That way, if you pass to samurai all you'd have to do is buy a couple pieces of heavy healing gear (like a scale and a sword) and then you would be set to heal until monk or ninja or whatever.
Just my 2 cents