I've got H&R race springs all around which have high spring rates in the front at like 750-850. However, with the Bilsteins, they ride just perfect and way better than stock. I've got MM C/C plates and DO NOT have any hint of bumpsteer. I'm only lowered about an inch, but the Bilsteins are the key to my setup.
I believe the Saleen springs have high rates also, but not sure. The higher they are the more critical it is to use matched shocks/struts.
I've had my suspension on for about a month and I actually prefer taking my car all the time over the other two cars in my garage: 2003 Mach 1 and an RSX. Handling and traction is great, plus almost no nose dive when braking moderately to hard.
Get the springs if you can get a good price, then save up until you can afford the other parts you need. Might as well put everything on at the same time, especially if you're paying for installation.
A good suspension makes most other mods that much better and safer. Nothing beats building hp on a good foundation.