Solid state drives are certainly nice - for your primary drive, but are most definitely not needed.
I had multiple SSD's on my monster machine, and got pissed off that they failed six months into having them, so I just went back to SATA III regular drives that spin at 7,200 rpm, and those work just fine for Sonar.
So, since money is an issue, I would suggest putting your money into a better CPU, such as an Intel i7, and into main memory, such as 2 8GB memory strips (16 GB - costs around $150, on average).
You can ALWAYS take your primary drive and clone it to a solid-state drive at some future point, without having to re-install anything, as long as you keep the size of what is loaded onto your pre-SSD primary drive limited to the OS and applications. That way, the clone will work, since the volume of what will be cloned is small enough to still fit on the new SSD drive.
Lots of folks, myself included, split where things are loaded, so that only the OS and applications are stored on the primary drive, and all data, like sample libraries and Cakewalk projects and such are all stored on one or more additional drives. This is good for performance, and great for switching out later to a solid-state primary drive when more money is available.
So, a 1 TB SATA III drive runs around $75 usd, and a 2 TB SATA III drive runs around $105 usd.
And for whatever the worth, I just use the on-board graphics to run 2 displays, and that works just fine. Again, you can always decide to add a video card later, if desired, but unless you are having issues using the on-board graphics, there is no need to do so.
Summarizing, I suggest an Intel i7 CPU, 16 GB of memory (as 2 8 GB strips, so later you an add 16 GB more for an eventual total of 32 GB), and a couple of SATA III 7,200 drives.
You should be able to get good quality components, like Seagate drives, and such, for a reasonable price.
Hope that helps,
Bob Bone