Kevin, Unless it's been well above room tempurature for extended periods of time your Kodachrome will come out just fine. As to the cost I'm not sure where you're sending it at $15 a whack, but the only Kodachrome processor in the world, Dwaynes, charges $10 per cartridge. That's only $30 plus $5 for priority mail. The best/cheapest way to get your K-chrome processed is to take it to Wal-Mart which costs only $4.88 and it will come back to your local Wal-Mart. Oh yeah guess where it ends up? Dwaynes via Fuji. Don't bother asking the photo clerk if they do it, they likely will say no or don't know. They do. Just put "Super 8 Film" on the envolope and it should find it's way to the nearest Fuji Lab and then to Dwaynes and back again. Should take 1-3 weeks.
Cheers,
James