Since you intend on shipping via Houston, then my guess is that you want your goods containerized.
It will cost you an average of $2000 ($1850 to $2400) per vehicle. My advice to you is to utilize shipping companies based in Houston to limit the hassle in handling your vehicle.
I can think of two companies based in that area.
1. Sifax:
http://www.sifaxgroup.com/contact.html ------ +1(713)263-8300,+1(713)263-8302
2. ADC:
http://adcshipping.com/ ----- +1(832) 816-8615