First off, when buying your magic, be sure to load up on bags of holding and such, 'cause you'll either be carrying around a lot of stuff or a lot of coin.
Now, for the rest of it. Lots and lots and lots of the mundane "extras" that often get overlooked:
Silver/iron/adamantium weapons.
Chain shirt PJs.
Portable Ram. Scratch that. Full-sized Ram.
Back up mounts.
Forget the bedroll, get an actual bed.
Tools. Carpentry. Metal working. Gardening. Whatever, just all of them.
An alchemists' lab.
Pack animals.
Back up pack animals.
Spyglass.
Water clock. Just 'cause.
More 10' poles than you could shake a 10' pole at.
Healers/climbers/disguise kits.
A pack of trained hunting dogs.
A wheelbarrow. And a holocaust cloak.
Boat/wagon/carriage/other vehicles.
Sunrods/Tanglefoot bags/Alchemists' Fire/etc.
And so on...
And since it sounds like you're a religious type, load up on holy symbols and texts and go all Jehovah's Witness on your DM.
Realize I'm halfway joking around with this, but there is a lot of mundane stuff you could load up on. I also think your Dm is being kind of silly making you spend that much on mundanes.