Agree about there being a difference in performance in favor of a SSD. Yes, RAID config with solid states can improve performance depending on the configuration. If you have the ports available and the cash, RAID5+1 gives you the redundancy, a hot spare and killer performance. Sadly, there aren't a lot of motherboards out there with 6 SATA ports of 1 variety (My ASUS 990FX has 6 SATAIII - waiting for the day I can afford 6 on my drives). Easiest way to get serious performance with a RAID config would be RAID 0 - you won't get any redundancy so if a disk fails you're fracked but you'll get killer read/write speeds because it's using 2 SSDs as a team to find/write data.
If price is a concern, it's important to determine exactly how much space you need for your program files and OS. For me, 120GB was more than enough. Then select a SSD you are interested in purchasing and either price shop between major vendors (Newegg, Amazon, Microcenter, etc.) and pick the cheaper of the group or just wait for a good sale.
If you have SATAIII ports on your motherboard, you definitely want to splurage for one. I am using a 120 GB Intel 520 series and it's phenomenal. I'll never go back to a HDD as my primary - I have it paired with a 1.5 TB HDD for all my documents and media. Best of both words.