Yikes!! If you can afford it go for it. I'd tip probably at least $50 minimum but would probably feel guilty, however if I could afford to spend $400 on my hair then I'd probably be able to afford to tip better.
The gal who cuts my hair charges $50 and I tip about $10. I pay $175 for full highlites and I tipped $20. When I get my nails done I tip $5 standard flat rate. Don't ask me why.