Sorry for ignoring your nose mount request, but if you're OK with a door mount, try Arnie Itzkowitz's Aerial Exposures platform:
Gyro Stabilized Video Film Camera Mount Platform Stabilized Video Film Camera Mount Gyro Stabilizer Video Film .
Priced from under $10k to about $50k, they're a cheap alternative to a Tyler Mount and require no STC to use in aircraft. They're quite portable and would work with a variety of cameras. If you're looking for a nose mount, you could go with the Tyler Nose Mount (which is a non-stabilized mount, and has control over tilt) or with a gyro ball. Is renting a gyro ball out of your budget? There are plenty of options available in HD, and in this economy you might have some room to bargain with the vendor...